Allow squashfs for vendor image only

Previously, the squashfs dependencies were included only if
the system image was squashfs.  Allow the vendor image trigger
the dependency.

Change-Id: I5b1c513e9c13d83efc3ca6a904f08a91d9cca85f
diff --git a/core/Makefile b/core/Makefile
index bc37369..1ee6549 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -754,7 +754,7 @@
 ifneq (true,$(TARGET_USERIMAGES_SPARSE_SQUASHFS_DISABLED))
   INTERNAL_USERIMAGES_SPARSE_SQUASHFS_FLAG := -s
 endif
-ifeq ($(BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE),squashfs)
+ifneq ($(filter $(BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE) $(BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE),squashfs),)
 INTERNAL_USERIMAGES_DEPS += $(MAKE_SQUASHFS) $(MKSQUASHFSUSERIMG) $(IMG2SIMG)
 endif