drm/bridge: check bridge power status before initialization

Only perform bridge power on when not initialized in bootloader to support
glitch free splash.

Change-Id: Ifad997cad07605ef4a1b7c92d67aa3329a218a64
Acked-by: Krishna Kishor Jha <kkishorj@qti.qualcomm.com>
Signed-off-by: Rahul Sharma <rahsha@codeaurora.org>