SF: Avoid wormhole clear for BLIT calls

Do not call GPU clear from SF when composition
type is BLIT as it'll be taken care in HAL.

Change-Id: Ia613eb9b824c6484ecc8c8fa4ee883545d8541b8
Merge pull request #3 from CyanogenMod/cm-11.0

SF: Avoid wormhole clear for BLIT calls