This patch reworks the console driver to ensure that each bootloader stage
initializes it independently. As a result, both BL3-1 and BL2 platform code
now calls console_init() instead of relying on BL1 to perform console setup

Fixes ARM-software/tf-issues#120

Change-Id: Ic4d66e0375e40a2fc7434afcabc8bbb4715c14ab