sq_ring_needs_enter: revert change to only enter if submit != 0

This reverts commit f0c5c54945ae92a00cdbb43bdf3abaeab6bd3a23.

Glauber reports a regressions for his polled setup with this change.
As it's purely speculative, just revert it.

Reported-by: Glauber Costa <glauber.costa@datadoghq.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed