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_samus_defconfig b/configs/chromebook_samus_defconfig
index 657a075..e08dffc 100644
--- a/configs/chromebook_samus_defconfig
+++ b/configs/chromebook_samus_defconfig
@@ -56,6 +56,7 @@
 CONFIG_USB=y
 CONFIG_DM_USB=y
 CONFIG_USB_STORAGE=y
+CONFIG_USB_KEYBOARD=y
 CONFIG_DM_VIDEO=y
 CONFIG_FRAMEBUFFER_SET_VESA_MODE=y
 CONFIG_FRAMEBUFFER_VESA_MODE_11A=y