ext4: Don't ask about supporting ext2/3 in ext4 if ext4 is not configured

Don't offer to build ext2/3 support into ext4 if ext4 itself is not
configured on.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/Kconfig

@@ -28,6 +28,7 @@ config EXT4_FS
 
 config EXT4_USE_FOR_EXT23
 	bool "Use ext4 for ext2/ext3 file systems"
+	depends on EXT4_FS
 	depends on EXT3_FS=n || EXT2_FS=n
 	default y
 	help