Since now the generic console_t structure holds the UART base address as
well, let's use that generic location and drop the UART driver specific
data structure at all.

Change-Id: I07a07677153d3671ced776671e4f107824d3df16
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

The code managing the console is the same for all the platforms
currently supported. Since it is unlikely to change in the future move
the code to an external file in the common directory.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Change-Id: I6df555ea82d483b4f08a4a1e2cb0a7488fbaa015