BROKEN: ARM: rpi: enable USB keyboard

This will allow the user to interact with U-Boot without a serial
console. Unfortunately this doesn't work at present; while USB Mass
Storage devices appear to work fine with U-Boot's DWC2 driver, USB
keyboard devices don't:-(

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Revert "BROKEN: ARM: rpi: enable USB keyboard"

This reverts commit 5504a530fe24b63489e49531f7d2a273b6f99fae.