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/mx28evk_defconfig b/configs/mx28evk_defconfig
index 42c6383..2ba394a 100644
--- a/configs/mx28evk_defconfig
+++ b/configs/mx28evk_defconfig
@@ -4,6 +4,7 @@
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
 CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_VIDEO=y
 CONFIG_FIT=y
 CONFIG_SYS_EXTRA_OPTIONS="ENV_IS_IN_MMC"
 CONFIG_BOOTDELAY=1