Set primary plane format to RGBX.

 Set primary plane format to RGBX.

 BZ: 33412

 This is the kernel part of patch to fix regression caused by HWC overlay + sprite blending
implementation. We have a hw issue in display controller to display RGBA plane. We can't set
it to RGBA if there only primary plane is displayed. This patch will set primary plane to RGBX
if no overlay displayed, other wise it is set to RGBA.

Change-Id: I1f74dfb2841df771e1b9a0b14d390b17eb49ab40
Signed-off-by: Marc Mao <marc.mao@intel.com>
Reviewed-on: http://android.intel.com:8080/47155
Reviewed-by: Xu, Randy <randy.xu@intel.com>
Reviewed-by: Hu, Austin <austin.hu@intel.com>
Reviewed-by: Ai, Ke <ke.ai@intel.com>
Tested-by: Tong, BoX <box.tong@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>