fb.h: Provide alternate screen_base pointer

Some drivers use member screen_base of struct fb_info to store non-
__iomem pointers, creating the need for ugly __force typecasts to
avoid sparse warnings. This adds an alternate pointer without the
__iomem qualifyer for this use.
Signed-off-by: Lars Svensson <lars1.svensson@sonymobile.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/fb.h

@@ -483,7 +483,10 @@ struct fb_info {
 #ifdef CONFIG_FB_TILEBLITTING
 	struct fb_tile_ops *tileops;    /* Tile Blitting */
 #endif
-	char __iomem *screen_base;	/* Virtual address */
+	union {
+		char __iomem *screen_base;	/* Virtual address */
+		char *screen_buffer;
+	};
 	unsigned long screen_size;	/* Amount of ioremapped VRAM or 0 */ 
 	void *pseudo_palette;		/* Fake palette of 16 colors */ 
 #define FBINFO_STATE_RUNNING	0