OMAPDSS: handle WB channel in dispc_set/get_channel_out

Add handling of OMAP_DSS_CHANNEL_WB to dispc_ovl_set_channel_out() and
dispc_ovl_get_channel_out().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/fbdev/omap2/dss/dispc.c b/drivers/video/fbdev/omap2/dss/dispc.c
index 678a192..4126d62 100644
--- a/drivers/video/fbdev/omap2/dss/dispc.c
+++ b/drivers/video/fbdev/omap2/dss/dispc.c
@@ -974,6 +974,10 @@
 				return;
 			}
 			break;
+		case OMAP_DSS_CHANNEL_WB:
+			chan = 0;
+			chan2 = 3;
+			break;
 		default:
 			BUG();
 			return;
@@ -1023,6 +1027,8 @@
 		return OMAP_DSS_CHANNEL_LCD2;
 	case 2:
 		return OMAP_DSS_CHANNEL_LCD3;
+	case 3:
+		return OMAP_DSS_CHANNEL_WB;
 	}
 }