hwc/overlay: Add Color layer support in MDP Composition.

1. Color layer has a destination rectangle, RGBA color and plane
   alpha. There is no gralloc buffer. Layer flag "HWC_COLOR_FILL"
   denotes a Color layer.
2. There is no color member in HWC layer, so RGBA color value
   is passed via the "tranform" member from framework to HAL.

Change-Id: I8769fd3f5febcaf952a1456de0a4262679c9a0e4
diff --git a/liboverlay/overlayCtrlData.h b/liboverlay/overlayCtrlData.h
index c3a7aa3..d34fd2d 100644
--- a/liboverlay/overlayCtrlData.h
+++ b/liboverlay/overlayCtrlData.h
@@ -61,6 +61,8 @@
     void setSource(const utils::PipeArgs& args);
     /* set crop info and pass it down to mdp */
     void setCrop(const utils::Dim& d);
+    /* set color for mdp pipe */
+    void setColor(const uint32_t color);
     /* set orientation */
     void setTransform(const utils::eTransform& p);
     /* set mdp position using dim */
@@ -174,6 +176,11 @@
     mMdp.setCrop(d);
 }
 
+inline void Ctrl::setColor(const uint32_t color)
+{
+    mMdp.setColor(color);
+}
+
 inline bool Ctrl::setVisualParams(const MetaData_t &metadata)
 {
     if (!mMdp.setVisualParams(metadata)) {