drm/msm/sde: fix to set the interfaces for cont splash

Current driver is not updating the correct interfaces
during the continuous splash case. Update the continuous
splash softwar to be able to read the interfaces enabled
for each controller.

Change-Id: I9318ee4434f1c59897aaaca499274287f8043f09
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>