Convert CONFIG_CMD_HDMIDETECT to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_HDMIDETECT

Note that we cannot do 'default y if VIDEO' because this option is only
enabled for a small subset of mx6 boards. Also this command is is not a
great implementation (it doesn't use driver model).

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/colibri_imx6_defconfig b/configs/colibri_imx6_defconfig
index 47e8198..6c10576 100644
--- a/configs/colibri_imx6_defconfig
+++ b/configs/colibri_imx6_defconfig
@@ -7,6 +7,7 @@
 CONFIG_SPL_MMC_SUPPORT=y
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_VIDEO=y
+CONFIG_CMD_HDMIDETECT=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/imx-common/spl_sd.cfg,MX6DL"
 CONFIG_BOOTDELAY=1
 # CONFIG_CONSOLE_MUX is not set