i.MX Framebuffer: Use readl/writel instead of direct pointer deref

This patch prepares the current i.MX1 framebuffer driver for usage in the
whole i.MX family. It switches to readl/writel for register accesses.
Also it moves the register definitions to the driver where they belong.

Acked-by: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Juergen Beisert <j.beisert@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/drivers/video/imxfb.h b/drivers/video/imxfb.h
index e837a8b..baa86a0 100644
--- a/drivers/video/imxfb.h
+++ b/drivers/video/imxfb.h
@@ -29,7 +29,8 @@
 #define NR_RGB	2
 
 struct imxfb_info {
-	struct device		*dev;
+	void __iomem		*regs;
+
 	struct imxfb_rgb	*rgb[NR_RGB];
 
 	u_int			max_bpp;