The UART used to be initialised in bl1_platform_setup(). This is too
late because there are some calls to the assert() macro, which needs
to print some messages on the console, before that.

This patch moves the UART initialisation code to
bl1_early_platform_setup().

Fixes ARM-software/tf-issues#49

Change-Id: I98c83a803866372806d2a9c2e1ed80f2ef5b3bcc