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/novena_defconfig b/configs/novena_defconfig
index 44d5b55..49b963c 100644
--- a/configs/novena_defconfig
+++ b/configs/novena_defconfig
@@ -10,6 +10,7 @@
 CONFIG_SPL_LIBDISK_SUPPORT=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_SPL_FAT_SUPPORT=y
+CONFIG_CMD_HDMIDETECT=y
 CONFIG_VIDEO=y
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT=y