gpu: nvgpu: add function to retrieve clk points

JIRA DNVGPU-123

Function will copy possible clock points for
a given master clock domain to pointer passed.
pointer with NULL value and count of zero can be passed
to query number of clock points for a given domain so that
memory can be allocated and function called again to
fill clock points

Change-Id: Iec6206f23789980036be99793599e934bd221035
Reviewed-on: http://git-master/r/1218912
(cherry picked from commit 9219697bff1e12deb605325055a02a7b387996e9)
Signed-off-by: Vijayakumar <vsubbu@nvidia.com>
Reviewed-on: http://git-master/r/1235055
Reviewed-by: Thomas Fleury <tfleury@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

drivers/gpu/nvgpu/clk/clk.h

@@ -92,5 +92,11 @@ u32 clk_domain_get_f_or_v
 	u16 *pclkmhz,
 	u32 *pvoltuv
 );
+u32 clk_domain_get_f_points(
+	struct gk20a *g,
+	u32 clkapidomain,
+	u32 *fpointscount,
+	u16 *freqpointsinmhz
+);
 
 #endif