Remove unused 'PL011_BASE' macro

'PL011_BASE' macro is no longer used because the right UART base
address is now directly given to the 'console_init()' function.
This patch removes it.

Change-Id: I94759c99602df4876291a56f9f6a75de337a65ec
Merge pull request #57 from sandrine-bailleux/sb/remove-pl011-base

Remove unused 'PL011_BASE' macro