Convert CONFIG_VIDEO to Kconfig

This converts the following to Kconfig:
   CONFIG_VIDEO

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Jagan Teki <jteki@openedev.com>
diff --git a/configs/colibri_imx7_defconfig b/configs/colibri_imx7_defconfig
index 4eca7b9..adf47c2 100644
--- a/configs/colibri_imx7_defconfig
+++ b/configs/colibri_imx7_defconfig
@@ -4,6 +4,7 @@
 CONFIG_IMX_RDC=y
 CONFIG_IMX_BOOTAUX=y
 CONFIG_DEFAULT_DEVICE_TREE="imx7-colibri"
+CONFIG_VIDEO=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/toradex/colibri_imx7/imximage.cfg,MX7D"
 CONFIG_BOOTDELAY=1
 # CONFIG_DISPLAY_BOARDINFO is not set