video: imxfb: Add DT default contrast control register property.

Signed-off-by: Denis Carikli <denis@eukrea.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

Documentation/devicetree/bindings/video/fsl,imx-fb.txt

@@ -18,6 +18,9 @@ Optional properties:
 - lcd-supply: Regulator for LCD supply voltage.
 - fsl,dmacr: DMA Control Register value. This is optional. By default, the
 	register is not modified as recommended by the datasheet.
+- fsl,lpccr: Contrast Control Register value. This property provides the
+	default value for the contrast control register.
+	If that property is ommited, the register is zeroed.
 - fsl,lscr1: LCDC Sharp Configuration Register value.
 
 Example:

drivers/video/imxfb.c

@@ -670,6 +670,9 @@ static int imxfb_init_fbinfo(struct platform_device *pdev)
 		fbi->cmap_static = of_property_read_bool(np, "cmap-static");
 
 		fbi->lscr1 = IMXFB_LSCR1_DEFAULT;
+
+		of_property_read_u32(np, "fsl,lpccr", &fbi->pwmr);
+
 		of_property_read_u32(np, "fsl,lscr1", &fbi->lscr1);
 
 		of_property_read_u32(np, "fsl,dmacr", &fbi->dmacr);