drm/msm: add timestamp param

We need this for GL_TIMESTAMP queries.

Note: currently only supported on a4xx.. a3xx doesn't have this
always-on counter.  I think we could emulate it with the one CP
counter that is available, but for now it is of limited usefulness
on a3xx (since we can't seem to do time-elapsed queries in any sane
way with the existing firmware on a3xx, and if you are trying to do
profiling on a tiler you want time-elapsed).  We can add that later
if it becomes useful.

Signed-off-by: Rob Clark <robdclark@gmail.com>

include/uapi/drm/msm_drm.h

@@ -51,6 +51,7 @@ struct drm_msm_timespec {
 #define MSM_PARAM_GMEM_SIZE  0x02
 #define MSM_PARAM_CHIP_ID    0x03
 #define MSM_PARAM_MAX_FREQ   0x04
+#define MSM_PARAM_TIMESTAMP  0x05
 
 struct drm_msm_param {
 	__u32 pipe;           /* in, MSM_PIPE_x */