video: mxsfb: add DM_VIDEO support

Extend the driver to build with DM_VIDEO enabled. DTS files
must additionally include 'u-boot,dm-pre-reloc' property in
soc and child nodes to enable driver binding to mxsfb device.

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
diff --git a/arch/arm/mach-imx/cpu.c b/arch/arm/mach-imx/cpu.c
index 6b83f92..64a0670 100644
--- a/arch/arm/mach-imx/cpu.c
+++ b/arch/arm/mach-imx/cpu.c
@@ -298,7 +298,7 @@
 	/* disable video before launching O/S */
 	ipuv3_fb_shutdown();
 #endif
-#if defined(CONFIG_VIDEO_MXS)
+#if defined(CONFIG_VIDEO_MXS) && !defined(CONFIG_DM_VIDEO)
 	lcdif_power_down();
 #endif
 }