display: Export headers

Display headers used by other components should be at a common
location to avoid issues with future changes in paths.

Change-Id: Iaec21206b82dd7dae03e598b9ec46b3e6f1bbf71
diff --git a/common.mk b/common.mk
index cefe060..02867d7 100644
--- a/common.mk
+++ b/common.mk
@@ -12,6 +12,8 @@
     common_includes += $(TARGET_OUT_HEADERS)/pp/inc
 endif
 
+common_header_export_path := qcom/display
+
 #Common libraries external to display HAL
 common_libs := liblog libutils libcutils libhardware