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/digsy_mtc_RAMBOOT_defconfig b/configs/digsy_mtc_RAMBOOT_defconfig
index d0743c8..9735986 100644
--- a/configs/digsy_mtc_RAMBOOT_defconfig
+++ b/configs/digsy_mtc_RAMBOOT_defconfig
@@ -1,4 +1,5 @@
 CONFIG_PPC=y
+CONFIG_VIDEO=y
 CONFIG_MPC5xxx=y
 CONFIG_TARGET_DIGSY_MTC=y
 CONFIG_OF_BOARD_SETUP=y