drm/omap: dsi: fix unreachable code in dsi_vc_send_short()

The 'r' in dsi_vc_send_short() is of type 'unsigned int', so the
'r < 0' can't be true.

Fix this by introducing a 'err' of type 'int' insteaded.

Fixes: 1ed62538 ("drm/omap: dsi: switch dsi_vc_send_long/short to mipi_dsi_msg")
Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210127015117.23267-1-dong.menglong@zte.com.cn

drivers/gpu/drm/omapdrm/dss/dsi.c

@@ -2149,11 +2149,12 @@ static int dsi_vc_send_short(struct dsi_data *dsi, int vc,
 			     const struct mipi_dsi_msg *msg)
 {
 	struct mipi_dsi_packet pkt;
+	int err;
 	u32 r;
 
-	r = mipi_dsi_create_packet(&pkt, msg);
-	if (r < 0)
-		return r;
+	err = mipi_dsi_create_packet(&pkt, msg);
+	if (err)
+		return err;
 
 	WARN_ON(!dsi_bus_is_locked(dsi));