mx6: Factor out common HDMI setup code

Instead of duplicating HDMI setup code for every mx6 board, factor out the common code

Signed-off-by: Pardeep Kumar Singla <b45784@freescale.com>
Acked-By: Eric Nelson <eric.nelson@boundarydevices.com>
diff --git a/include/configs/nitrogen6x.h b/include/configs/nitrogen6x.h
index 85eecfc..b057039 100644
--- a/include/configs/nitrogen6x.h
+++ b/include/configs/nitrogen6x.h
@@ -154,6 +154,7 @@
 #define CONFIG_IPUV3_CLK 260000000
 #define CONFIG_CMD_HDMIDETECT
 #define CONFIG_CONSOLE_MUX
+#define CONFIG_IMX_HDMI
 
 /* allow to overwrite serial and ethaddr */
 #define CONFIG_ENV_OVERWRITE