fiq_debugger: Call fiq_debugger_printf through a function pointer from cpu specific code

This allows the output from the register and stack trace code to be
sent elsewhere.

Change-Id: I41bb0d5a25e1b9ca55feef5dbd675818b2f832d5
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Git-commit: 4498669afbf036ce296df6165fa1c46e23dc57c9
Git-repo: https://android.googlesource.com/kernel/common.git


Signed-off-by: Ian Maund <imaund@codeaurora.org>