Add PL011 UART driver

A minimal PL011 driver containing necessary functions
to print to UART. Based on the assembly implementation
found in TF-A (hash: 39bcbeac9c8c20ae660cb6d9e825ceb01e6144e7;
file: drivers/arm/pl011/aarch64/pl011_console.S).

Signed-off-by: Gabor Toth <gabor.toth2@arm.com>
Signed-off-by: Gabor Ambrus <gabor.ambrus@arm.com>
Change-Id: I644fb011b2b9a68aa09e8cc3a09ebd8b9576bb30
8 files changed