ltp/fsstress: don't fail on io_uring ENOSYS

ltp/fsstress: don't fail on io_uring ENOSYS

We might have URING #defined at build time, but be running on a kernel
which does not support it.

For that reason, we should not exit with an error if
io_uring_queue_init() fails with ENOSYS. We can just note the lack of
support and skip all future io_uring operations.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>