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/MIP405_defconfig b/configs/MIP405_defconfig
index 3eb5ddf..eee1811 100644
--- a/configs/MIP405_defconfig
+++ b/configs/MIP405_defconfig
@@ -21,5 +21,6 @@
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y
+CONFIG_USB_KEYBOARD=y
 CONFIG_CONSOLE_EXTRA_INFO=y
 CONFIG_VIDEO_CT69000=y