fcntl: don't leak fd reference when fixup_compat_flock fails

[ Upstream commit 9280a601e6080c9ff658468c1c775ff6514099a6 ]

Currently we just return err here, but we need to put the fd reference
first.

Fixes: 94073ad7 (fs/locks: don't mess with the address limit in compat_fcntl64)
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>