Fix typo of PRODUCT_BUILD_PRODUCT_SERVICES_IMAGE

Test: treehugger
Change-Id: I087d865c12d9aff7bdc0018256c1a87657d8550c
diff --git a/core/envsetup.mk b/core/envsetup.mk
index 390a182..bd632bf 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -465,7 +465,7 @@
 endif
 
 BUILDING_PRODUCT_SERVICES_IMAGE :=
-ifeq ($(PRODUCT_SERVICES_BUILD_PRODUCT_SERVICES_IMAGE),)
+ifeq ($(PRODUCT_BUILD_PRODUCT_SERVICES_IMAGE),)
   ifdef BOARD_PRODUCT_SERVICESIMAGE_FILE_SYSTEM_TYPE
     BUILDING_PRODUCT_SERVICES_IMAGE := true
   endif