sdm: Add interface for rotator load sharing.

Add interface to store writeback id and the pipe id for rotator
load sharing

Change-Id: I19142e9823a569aaff3afdf88017f7c36bbf4e27
diff --git a/sdm/include/private/hw_info_types.h b/sdm/include/private/hw_info_types.h
index 3360fb4..ab6e9f9 100644
--- a/sdm/include/private/hw_info_types.h
+++ b/sdm/include/private/hw_info_types.h
@@ -198,15 +198,15 @@
 };
 
 struct HWRotateInfo {
-  uint32_t pipe_id;
+  int pipe_id;
+  int writeback_id;
   LayerRect src_roi;
   LayerRect dst_roi;
-  HWBlockType writeback_id;
   bool valid;
   int rotate_id;
 
   HWRotateInfo()
-    : pipe_id(0), writeback_id(kHWWriteback0), valid(false), rotate_id(-1) { }
+    : pipe_id(-1), writeback_id(-1), valid(false), rotate_id(-1) { }
 
   void Reset() { *this = HWRotateInfo(); }
 };