io_uring/register: have io_parse_restrictions() set restrictions enabled
Rather than leave this to the caller, have io_parse_restrictions() set
->registered = true if restrictions have been enabled. This is in
preparation for having finer grained restrictions.
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>