drm/msm: update debug support in msm drm driver

MSM drm driver creates multiple debug directories
for debug support; "evt_dbg", "debug", etc. This
patch unifies the debug support and creates all
debug file nodes within root "debug" folder. It
also fixes the event logging and pixel format
message logging.

Change-Id: Ie23e76b2e4b4aaceadf2c2afe6a4d9c6cc629bb3
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>