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

Also perform the console initialisation earlier in BL1 because
it must be done before it is used e.g. through a printf() call
in an assert() statement.

Change-Id: I8bb58cf1f0e42a71a01abf65da30bfa4ae533665