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/tbs2910_defconfig b/configs/tbs2910_defconfig
index 0871408..e86b781 100644
--- a/configs/tbs2910_defconfig
+++ b/configs/tbs2910_defconfig
@@ -3,6 +3,7 @@
 CONFIG_TARGET_TBS2910=y
 CONFIG_PRE_CONSOLE_BUFFER=y
 CONFIG_PRE_CON_BUF_ADDR=0x7c000000
+CONFIG_VIDEO=y
 CONFIG_FIT=y
 CONFIG_BOOTDELAY=3
 CONFIG_HUSH_PARSER=y