OMAPFB: 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>

drivers/video/omap2/omapfb/omapfb-main.c

@@ -179,6 +179,7 @@ static unsigned omapfb_get_vrfb_offset(const struct omapfb_info *ofbi, int rot)
 		break;
 	default:
 		BUG();
+		return 0;
 	}
 
 	offset *= vrfb->bytespp;

drivers/video/omap2/omapfb/omapfb.h

@@ -166,6 +166,7 @@ static inline struct omapfb_display_data *get_display_data(
 
 	/* This should never happen */
 	BUG();
+	return NULL;
 }
 
 static inline void omapfb_lock(struct omapfb2_device *fbdev)