media: v4l: cadence: Fix how unsued lanes are handled in 'csi2rx_start()'

The 2nd parameter of 'find_first_zero_bit()' is a number of bits, not of
bytes. So use 'csi2rx->max_lanes' instead of 'sizeof(lanes_used)'.

Fixes: 1fc3b37f34f6 ("media: v4l: cadence: Add Cadence MIPI-CSI2 RX driver")
Signed-off-by: Christophe JAILLET <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/platform/cadence/cdns-csi2rx.c

···
 	 */
 	for (i = csi2rx->num_lanes; i < csi2rx->max_lanes; i++) {
 		unsigned int idx = find_first_zero_bit(&lanes_used,
-						       sizeof(lanes_used));
+						       csi2rx->max_lanes);
 		set_bit(idx, &lanes_used);
 		reg |= CSI2RX_STATIC_CFG_DLANE_MAP(i, i + 1);
 	}