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/arch/arm/imx-common/Kconfig b/arch/arm/imx-common/Kconfig
index 25cbd12..cd8b8d2 100644
--- a/arch/arm/imx-common/Kconfig
+++ b/arch/arm/imx-common/Kconfig
@@ -55,3 +55,9 @@
 	  Freescale secure boot mechanism. This command encapsulates and
 	  creates a blob of data. See also CMD_BLOB and doc/README.mxc_hab for
 	  more information.
+
+config CMD_HDMIDETECT
+	bool "Support the 'hdmidet' command"
+	help
+	  This enables the 'hdmidet' command which detects if an HDMI monitor
+	  is connected.