sdm: Fix compilation errors.

Change-Id: I5155bc649492caac3d2cb0873ab6b90d95c35201
diff --git a/sdm/include/utils/constants.h b/sdm/include/utils/constants.h
index a73bce6..57c5a86 100644
--- a/sdm/include/utils/constants.h
+++ b/sdm/include/utils/constants.h
@@ -89,6 +89,7 @@
   const int kThreadPriorityUrgent = -9;
   const int kMaxRotatePerLayer = 2;
   const uint32_t kMaxBlitTargetLayers = 2;
+  const int kPageSize = 4096;
 
   typedef void * Handle;