nvgpu: fix static sparse warnings

Fixed below static sparse warnings by making either
function as static or including right header.

- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/common/linux/module.c:816:5: warning: symbol 'gk20a_pm_init' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gk20a/bus_gk20a.c:28:6: warning: symbol 'gk20a_bus_init_hw' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gk20a/bus_gk20a.c:54:6: warning: symbol 'gk20a_bus_isr' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gk20a/bus_gk20a.c:90:5: warning: symbol 'gk20a_read_ptimer' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gk20a/bus_gk20a.c:147:6: warning: symbol 'gk20a_init_bus' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gk20a/ltc_gk20a.c:232:6: warning: symbol 'gk20a_init_ltc' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gk20a/fb_gk20a.c:75:6: warning: symbol 'gk20a_fb_debug_mode_enabled' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gm20b/hal_gm20b.c:184:5: warning: symbol 'gm20b_init_hal' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gm20b/fb_gm20b.c:165:5: warning: symbol 'gm20b_fb_vpr_info_fetch' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gm20b/ltc_gm20b.c:103:5: warning: symbol 'gm20b_ltc_cbc_ctrl' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gm20b/ltc_gm20b.c:168:6: warning: symbol 'gm20b_ltc_init_fs_state' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gm20b/ltc_gm20b.c:195:6: warning: symbol 'gm20b_ltc_isr' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gm20b/ltc_gm20b.c:221:5: warning: symbol 'gm20b_ltc_cbc_fix_config' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gm20b/ltc_gm20b.c:236:6: warning: symbol 'gm20b_flush_ltc' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gm20b/ltc_gm20b.c:350:6: warning: symbol 'gm20b_init_ltc' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/tegra/linux/clk.c:72:6: warning: symbol 'nvgpu_linux_init_clk_support' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gp10b/ltc_gp10b.c:206:6: warning: symbol 'gp10b_init_ltc' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gp10b/fb_gp10b.c:98:6: warning: symbol 'gp10b_init_fb' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gp10b/hal_gp10b.c:190:5: warning: symbol 'gp10b_init_hal' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gp10b/priv_ring_gp10b.c:79:6: warning: symbol 'gp10b_init_priv_ring' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gp106/hal_gp106.c:222:5: warning: symbol 'gp106_init_hal' was not declared. Should it be static?
- $TOP/kernel/nvgpu/drivers/gpu/nvgpu/gp106/fb_gp106.c:42:6: warning: symbol 'gp106_init_fb' was not declared. Should it be static?

Bug 200299572

Change-Id: I32f9a3cb65314bd1eb1a6d93cda5796cfa64d738
Signed-off-by: Sachin Nikam <snikam@nvidia.com>
Reviewed-on: http://git-master/r/1481804
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/linux/module.c

@@ -809,7 +809,7 @@ static const struct dev_pm_ops gk20a_pm_ops = {
 };
 #endif
 
-int gk20a_pm_init(struct device *dev)
+static int gk20a_pm_init(struct device *dev)
 {
 	struct gk20a *g = get_gk20a(dev);
 	int err = 0;