gpu: nvgpu: move cycle state buffer handler to linux

We use dma_buf pointer cyclestate_buffer_handler in common code
But since this is linux specific, we need to move this out of common code and
into linux specific code

Move dma_buf pointer cyclestate_buffer_handler from common channel code to
struct nvgpu_channel_linux

Fix all pointer accesses to this handle

Move gk20a_channel_free_cycle_stats_buffer() to ioctl_channel.c since it is
mostly linux specific
And since gk20a_channel_free_cycle_stats_buffer() needs to be called while
closing the channel, call it from nvgpu_channel_close_linux()

Jira NVGPU-397
Jira NVGPU-415

Change-Id: Ifb429e49b8f7a1c9e2bc757f3efdd50b28ceca1f
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1603909
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/linux/channel.h

@@ -17,6 +17,7 @@
 #define __NVGPU_CHANNEL_H__
 
 #include <linux/workqueue.h>
+#include <linux/dma-buf.h>
 
 #include <nvgpu/types.h>
 
@@ -56,6 +57,8 @@ struct nvgpu_channel_linux {
 
 	struct nvgpu_channel_completion_cb completion_cb;
 	struct nvgpu_error_notifier error_notifier;
+
+	struct dma_buf *cyclestate_buffer_handler;
 };
 
 int nvgpu_init_channel_support_linux(struct nvgpu_os_linux *l);