drm/msm/sde: update initial clock value for continuous splash

If continuous splash is enabled for multiple displays, driver
votes for minimum core-clock as soon as one display gets the
disable call. Avoid this case by initializing the core-clock
in each crtc with max clock value during continuous splash.
This ensures the clocks are left at max until each display
processes one frame or disable.

Change-Id: I9ef1565ff4f58e1c78cef0c4cf38535f77f3f072
Signed-off-by: Prabhanjan Kandula <pkandula@codeaurora.org>