sdm: Fix layer blending parameter setting.

Set layer blending as BLEND_OP_OPAQUE for opaque layers.

CRs-Fixed: 957373
Change-Id: I559b8e185d7352d6ffcc05d6f5e3ea93d977409a
diff --git a/sdm/libs/core/fb/hw_device.cpp b/sdm/libs/core/fb/hw_device.cpp
index 246e08e..d947009 100644
--- a/sdm/libs/core/fb/hw_device.cpp
+++ b/sdm/libs/core/fb/hw_device.cpp
@@ -583,6 +583,7 @@
 void HWDevice::SetBlending(const LayerBlending &source, mdss_mdp_blend_op *target) {
   switch (source) {
   case kBlendingPremultiplied:  *target = BLEND_OP_PREMULTIPLIED;   break;
+  case kBlendingOpaque:         *target = BLEND_OP_OPAQUE;          break;
   case kBlendingCoverage:       *target = BLEND_OP_COVERAGE;        break;
   default:                      *target = BLEND_OP_NOT_DEFINED;     break;
   }