libgralloc: Enable UBWC output buffers for Writeback displays

While allocating output buffers for writeback display, check MDP
support for writeback UBWC format before assigning the format.

Change-Id: I97bb320ec89d60453c4c7e3dc5a2b5c2a18394dd
diff --git a/libqdutils/qd_utils.h b/libqdutils/qd_utils.h
index 0392e05..4722dcd 100644
--- a/libqdutils/qd_utils.h
+++ b/libqdutils/qd_utils.h
@@ -49,6 +49,7 @@
 enum HWQueryType {
     HAS_MACRO_TILE = 0,
     HAS_UBWC = 1,
+    HAS_WB_UBWC = 2
 };
 
 enum {