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/tbs2910_defconfig b/configs/tbs2910_defconfig
index e462283..da042ae 100644
--- a/configs/tbs2910_defconfig
+++ b/configs/tbs2910_defconfig
@@ -4,6 +4,7 @@
 CONFIG_TARGET_TBS2910=y
 CONFIG_PRE_CONSOLE_BUFFER=y
 CONFIG_VIDEO=y
+CONFIG_CMD_HDMIDETECT=y
 CONFIG_FIT=y
 CONFIG_BOOTDELAY=3
 CONFIG_PRE_CON_BUF_ADDR=0x7c000000