gralloc: Set default value for implementation defined formats

For implementation defined formats which go via HWC, set the
default value to RGBA8888

Change-Id: I7f8c46bc47746dcf1c4a03438b8f93d7bab78bb1
diff --git a/libgralloc/gpu.cpp b/libgralloc/gpu.cpp
index da179f9..bb7060b 100644
--- a/libgralloc/gpu.cpp
+++ b/libgralloc/gpu.cpp
@@ -282,13 +282,9 @@
             grallocFormat = HAL_PIXEL_FORMAT_YCrCb_420_SP; //NV21
         else if(usage & GRALLOC_USAGE_HW_CAMERA_WRITE)
             grallocFormat = HAL_PIXEL_FORMAT_YCrCb_420_SP; //NV21
-    }
-
-    if (format == HAL_PIXEL_FORMAT_IMPLEMENTATION_DEFINED &&
-            (usage & GRALLOC_USAGE_HW_COMPOSER )) {
-        //XXX: If we still haven't set a format, default to
-        //RGBA8888
-        grallocFormat = HAL_PIXEL_FORMAT_RGBA_8888;
+        else if(usage & GRALLOC_USAGE_HW_COMPOSER)
+            //XXX: If we still haven't set a format, default to RGBA8888
+            grallocFormat = HAL_PIXEL_FORMAT_RGBA_8888;
     }
 
     getGrallocInformationFromFormat(grallocFormat, &bufferType);