[PATCH] compat_sys_vmsplice: one-off in UIO_MAXIOV check

nr_segs may not be > UIO_MAXIOV, however it may be equal to. This makes
the behaviour identical to the real sys_vmsplice(). The other foov
syscalls also agree that this is the way to go.

Signed-off-by: Jens Axboe <axboe@suse.de>