msm: kgsl: Add MPDCVS trace events

These trace events help in detecting whether we are reporting the
right events(busy/idle) to the mpdcvs driver, effectively improving
debugging capabilities. The mpdcvs driver should get a busy event
when the gpu is active and an idle event whenever gpu goes idle.

Change-Id: Ie227343e764e5c7bce1c95f75668bf6326d62e7a
Signed-off-by: Suman Tatiraju <sumant@codeaurora.org>