Convert CONFIG_USB_KEYBOARD to Kconfig

This converts the following to Kconfig:
   CONFIG_USB_KEYBOARD

Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Fixup MPC86* configs]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ventana_defconfig b/configs/ventana_defconfig
index 33ca0bd..c86c0d9 100644
--- a/configs/ventana_defconfig
+++ b/configs/ventana_defconfig
@@ -39,6 +39,7 @@
 CONFIG_USB_ULPI_VIEWPORT=y
 CONFIG_USB_ULPI=y
 CONFIG_USB_STORAGE=y
+CONFIG_USB_KEYBOARD=y
 CONFIG_DM_VIDEO=y
 CONFIG_VIDEO_TEGRA20=y
 CONFIG_CONSOLE_SCROLL_LINES=10