s390/qdio: replace shift loop by ilog2

account_sbals is called by get_inbound_buffer_frontier and
get_outbound_buffer_frontier with 'count' value > 0 so we can safely
convert shift loop to ilog2.

Cc: Joe Perches <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Signed-off-by: Fabian Frederick <[e-mail]>
Signed-off-by: Sebastian Ott <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

drivers/s390/cio/qdio_main.c

···
 		set_buf_state(q, q->u.in.ack_start, SLSB_P_INPUT_NOT_INIT);
 }
 
-static inline void account_sbals(struct qdio_q *q, int count)
+static inline void account_sbals(struct qdio_q *q, unsigned int count)
 {
-	int pos = 0;
+	int pos;
 
 	q->q_stats.nr_sbal_total += count;
 	if (count == QDIO_MAX_BUFFERS_MASK) {
 		q->q_stats.nr_sbals[7]++;
 		return;
 	}
-	while (count >>= 1)
-		pos++;
+	pos = ilog2(count);
 	q->q_stats.nr_sbals[pos]++;
 }