refactor(drivers/pl011): Use the console driver

The patch refactors the pl011 driver to use the console
driver framework. The printf() implementation is modified
to use the console driver.

Signed-off-by: Harry Moulton <harry.moulton@arm.com>
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Change-Id: I7177fc013d2cb848cd82051f41f6462e47774557