omapfb: HWA742: fix pointer to be const

Fixes the following:
warning: assignment discards qualifiers from pointer target type

Signed-off-by: Imre Deak <imre.deak@nokia.com>
Acked-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/omap/hwa742.c

@@ -131,7 +131,7 @@ struct {
 
 	struct omapfb_device	*fbdev;
 	struct lcd_ctrl_extif	*extif;
-	struct lcd_ctrl		*int_ctrl;
+	const struct lcd_ctrl	*int_ctrl;
 
 	struct clk		*sys_ck;
 } hwa742;