pl011 UART: Move under drivers/uart

Currently this is only a minimal stub to get console on qemu-armv7.

Change-Id: I3f20b7f944bc7d0e5ace9d22198d4c16a3839d2c
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5162
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
5 files changed