ARM: brcmstb: revert SMP support

There were several issues (of varying degree of importance) pointed out
with this code late in the review cycle, yet the code was still merged.
Let's rip it out for now and look at resubmitting at a later time.

This reverts most of commit 4fbe66d9.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>