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/chromebook_link_defconfig b/configs/chromebook_link_defconfig
index 1ba72a8..782123b 100644
--- a/configs/chromebook_link_defconfig
+++ b/configs/chromebook_link_defconfig
@@ -58,6 +58,7 @@
 CONFIG_DM_USB=y
 CONFIG_USB_STORAGE=y
 CONFIG_DM_VIDEO=y
+CONFIG_USB_KEYBOARD=y
 CONFIG_VIDEO_VESA=y
 CONFIG_FRAMEBUFFER_SET_VESA_MODE=y
 CONFIG_FRAMEBUFFER_VESA_MODE_11A=y