xfs-convert-buftarg-lru-to-generic-code-fix

fix warnings

Cc: Dave Chinner <dchinner@redhat.com>
Cc: Glauber Costa <glommer@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>