s390/qdio: remove unneeded sanity check in qdio_do_sqbs()

All callers of set_buf_states() are already making sure that 'count'
is not 0. So don't check it an additional time.

Note that our own code also doesn't _require_ the count to be sane
(ie. we can't overrun an array or similar). So worst case HW would
simply reject the SQBS operation and report an error.

Signed-off-by: Julian Wiedmann <[e-mail]>
Reviewed-by: Benjamin Block <[e-mail]>
Signed-off-by: Heiko Carstens <[e-mail]>

drivers/s390/cio/qdio_main.c

···
 	int tmp_count = count, tmp_start = start;
 	int nr = q->nr;
 
-	if (!count)
-		return 0;
 	qperf_inc(q, sqbs);
 
 	if (!q->is_input_q)