OMAPDSS: remove compiler warnings when CONFIG_BUG=n

If CONFIG_BUG is not enabled, BUG() does not stop the execution. Many
places in code expect the execution to stop, and this causes compiler
warnings about uninitialized variables and returning from a non-void
function without a return value.

This patch fixes the warnings by initializing the variables and
returning properly after BUG() lines. However, the behaviour is still
undefined after the BUG, but this is the choice the user makes when
using CONFIG_BUG=n.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/dsi.c b/drivers/video/omap2/dss/dsi.c
index f2d835f..ec363d8 100644
--- a/drivers/video/omap2/dss/dsi.c
+++ b/drivers/video/omap2/dss/dsi.c
@@ -446,6 +446,7 @@
 		return 16;
 	default:
 		BUG();
+		return 0;
 	}
 }
 
@@ -2003,6 +2004,7 @@
 		return 1365 * 3;	/* 1365x24 bits */
 	default:
 		BUG();
+		return 0;
 	}
 }
 
@@ -2415,6 +2417,7 @@
 		if (add + size > 4) {
 			DSSERR("Illegal FIFO configuration\n");
 			BUG();
+			return;
 		}
 
 		v = FLD_VAL(add, 2, 0) | FLD_VAL(size, 7, 4);
@@ -2447,6 +2450,7 @@
 		if (add + size > 4) {
 			DSSERR("Illegal FIFO configuration\n");
 			BUG();
+			return;
 		}
 
 		v = FLD_VAL(add, 2, 0) | FLD_VAL(size, 7, 4);
@@ -2588,6 +2592,7 @@
 		return dsi_sync_vc_l4(dsidev, channel);
 	default:
 		BUG();
+		return -EINVAL;
 	}
 }
 
@@ -3156,6 +3161,7 @@
 		data = reqdata[0] | (reqdata[1] << 8);
 	} else {
 		BUG();
+		return -EINVAL;
 	}
 
 	r = dsi_vc_send_short(dsidev, channel, data_type, data, 0);
@@ -3270,7 +3276,6 @@
 		goto err;
 	}
 
-	BUG();
 err:
 	DSSERR("dsi_vc_read_rx_fifo(ch %d type %s) failed\n", channel,
 		type == DSS_DSI_CONTENT_GENERIC ? "GENERIC" : "DCS");
@@ -3879,6 +3884,7 @@
 		break;
 	default:
 		BUG();
+		return -EINVAL;
 	}
 
 	r = dsi_read_reg(dsidev, DSI_CTRL);
@@ -4119,6 +4125,7 @@
 			break;
 		default:
 			BUG();
+			return -EINVAL;
 		};
 
 		dsi_if_enable(dsidev, false);