Allow flashing a squashfs system image

Change-Id: Ic51d11274784a8d2e9d57d5f0b821ebc89680e5a
Signed-off-by: Mohamad Ayyash <mkayyash@google.com>
diff --git a/core/product.mk b/core/product.mk
index 3d2b6b9..d3df582 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -252,6 +252,7 @@
 	BOARD_BOOTIMAGE_PARTITION_SIZE \
 	BOARD_RECOVERYIMAGE_PARTITION_SIZE \
 	BOARD_SYSTEMIMAGE_PARTITION_SIZE \
+	BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE \
 	BOARD_USERDATAIMAGE_FILE_SYSTEM_TYPE \
 	BOARD_USERDATAIMAGE_PARTITION_SIZE \
 	BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE \