drm/bridge: tc358767: fix AUXDATAn registers access

First four bytes should go to DP0_AUXWDATA0. Due to bug if
len > 4 first four bytes was writen to DP0_AUXWDATA1 and all
data get shifted by 4 bytes. Fix it.

Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Andrey Gusakov <andrey.gusakov@cogentembedded.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1510073785-16108-6-git-send-email-andrey.gusakov@cogentembedded.com

drivers/gpu/drm/bridge/tc358767.c

@@ -318,7 +318,7 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux,
 				tmp = (tmp << 8) | buf[i];
 			i++;
 			if (((i % 4) == 0) || (i == size)) {
-				tc_write(DP0_AUXWDATA(i >> 2), tmp);
+				tc_write(DP0_AUXWDATA((i - 1) >> 2), tmp);
 				tmp = 0;
 			}
 		}