convert buf-ring nop test to use read

The NOP support for IOSQE_BUFFER_SELECT has been reverted, so use a
supported function with read. This also allows verifying that the
correct data has actually been read.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220615113733.1424472-1-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed