drm/msm/dsi-staging: fix idle power collapse exit sequence for PHY v3

Ensure that the escape clock is turned on prior to reinitializing
the DSI PHY when exiting idle power collapse. This will ensure that
there are no spurious transitions on the lanes after the PHY clamps
are removed.

Change-Id: Ic7ce1af62581b71d2a610b18381c9c57eb80696c
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>