fsstress: check io_uring_queue_init errno properly

fsstress: check io_uring_queue_init errno properly

As the manual of io_uring_queue_init says "io_uring_queue_init(3)
returns 0 on success and -errno on failure". We should check if the
return value is -ENOSYS, not the errno.

Fixes: d15b1721f284 ("ltp/fsstress: don't fail on io_uring ENOSYS")
Signed-off-by: Zorro Lang <zlang@redhat.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>