Fix it so we once again build the target root_fs

target/squashfs/Config.in

@@ -0,0 +1,6 @@
+config BR2_TARGET_ROOTFS_SQUASHFS
+	bool "squashfs root filesystem for the target device"
+	default n
+	help
+	  Build a squashfs root filesystem
+

target/squashfs/Makefile.in

@@ -0,0 +1,3 @@
+ifeq ($(strip $(BR2_TARGET_ROOTFS_SQUASHFS)),y)
+TARGETS+=squashfsroot
+endif