CIFS ACL support needs CONFIG_KEYS, so depend on it

Build fails if CONFIG_KEYS is not selected.
Signed-off-by: Darren Salt <linux@youmustbejoking.demon.co.uk>
Reviewed-by: Shirish Pargaonkar <shirishp@us.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/Kconfig

@@ -149,7 +149,7 @@ config CIFS_FSCACHE
 
 config CIFS_ACL
 	  bool "Provide CIFS ACL support (EXPERIMENTAL)"
-	  depends on EXPERIMENTAL && CIFS_XATTR
+	  depends on EXPERIMENTAL && CIFS_XATTR && KEYS
 	  help
 	    Allows to fetch CIFS/NTFS ACL from the server.  The DACL blob
 	    is handed over to the application/caller.