libc2dcolorconvert: Use pre-multiplied flag for RGBA8888 format

RGBA frames coming to encoder have premultipled alpha. Without
this flag C2D would interpret alpha channel, and if not set (like
mdp comp), video encode during wifi display session results in
black frames on secondary display.

Change-Id: Ib47d2b9021e2606bc467784db2367589feb2f97e
1 file changed