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/at91rm9200ek_defconfig b/configs/at91rm9200ek_defconfig
index e6569aa..b6db8c4 100644
--- a/configs/at91rm9200ek_defconfig
+++ b/configs/at91rm9200ek_defconfig
@@ -16,4 +16,5 @@
 CONFIG_CMD_FAT=y
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y
+CONFIG_USB_KEYBOARD=y
 CONFIG_OF_LIBFDT=y