msm_fb: Disable LCDC/DSI Video timing generator during boot up

Disable LCDC and DSI Video timing generator during MDP
initialization if continuous splash screen is disabled.

Change-Id: I64276550f28e1f316c420f9cb158f7b8e938b8ea
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>