hwc/overlay: Add support for pipe priorities, 1 pipe config for FB

If using source split to stage 2 pipes on the same mixer stage,
the left pipe needs to be a higher priority than the right.

Add API in overlay to compare pipe priorities and use this in
source split config to stage pipes accordingly.

Add support for 1 pipe config for FB if updating rect is within 2048
pixels.

Change-Id: I8b33d5ebd0f8765ee842bab128d8abd67a110145
diff --git a/liboverlay/overlayCtrlData.h b/liboverlay/overlayCtrlData.h
index 26202ec..51209a7 100644
--- a/liboverlay/overlayCtrlData.h
+++ b/liboverlay/overlayCtrlData.h
@@ -79,6 +79,8 @@
     void setDownscale(int dscale_factor);
     /* Update the src format based on rotator's dest */
     void updateSrcFormat(const uint32_t& rotDstFormat);
+    /* return pipe priority */
+    uint8_t getPriority() const;
     /* dump the state of the object */
     void dump() const;
     /* Return the dump in the specified buffer */
@@ -208,6 +210,10 @@
     mMdp->setDownscale(dscale_factor);
 }
 
+inline uint8_t Ctrl::getPriority() const {
+    return mMdp->getPriority();
+}
+
 inline void Ctrl::getDump(char *buf, size_t len) {
     mMdp->getDump(buf, len);
 }