Use my-dir in a consistent way as others

Change-Id: I3fd0cc58b48d621b431d7dd05fb689c1917b530d
diff --git a/core/definitions.mk b/core/definitions.mk
index 975b6b5..17c8089 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -154,7 +154,7 @@
 
 # $(1): List of directories to look for under this directory
 define all-named-subdir-makefiles
-$(wildcard $(addsuffix /Android.mk, $(addprefix $(my-dir)/,$(1))))
+$(wildcard $(addsuffix /Android.mk, $(addprefix $(call my-dir)/,$(1))))
 endef
 
 ###########################################################