io_uring: move io_uring_rsrc_update2 validation

[ Upstream commit 565c5e61

 ]

Move validation to be more consistently straight after
copy_from_user. This is already done in io_register_rsrc_update and so
this removes that redundant check.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220412163042.2788062-2-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>