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/mx6cuboxi_defconfig b/configs/mx6cuboxi_defconfig
index b2c59a4..3f00773 100644
--- a/configs/mx6cuboxi_defconfig
+++ b/configs/mx6cuboxi_defconfig
@@ -34,4 +34,5 @@
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y
 # CONFIG_VIDEO_SW_CURSOR is not set
+CONFIG_USB_KEYBOARD=y
 CONFIG_OF_LIBFDT=y