hwc: Enable sync-pt for rotator on B-family

Enable sync-pt for rotator on B-family. The already existing
MSMFB_BUF_SYNC ioctl is used, with an extra member for session_id
from rotator.

Change-Id: Ib0ef6b1bc5cf1e6437090a217d7f731a3440f84b
diff --git a/liboverlay/overlayRotator.h b/liboverlay/overlayRotator.h
index a600732..f551f1d 100644
--- a/liboverlay/overlayRotator.h
+++ b/liboverlay/overlayRotator.h
@@ -237,11 +237,11 @@
      * Expects a NULL terminated buffer of big enough size.
      */
     void getDump(char *buf, size_t len);
-    int getRotDevFd(); //Called on A-fam only
+    int getRotDevFd();
 private:
     overlay::Rotator *mRot[MAX_ROT_SESS];
     int mUseCount;
-    int mRotDevFd; //A-fam
+    int mRotDevFd;
 };