Code Review - Check code for oddities, improvements, inconsistencies, bugs, ...

Mostly reported by DeltaV : 

* check why syscall instructions lose parameters somewhere down the line
* check write32 in pll setup. maybe use set32 or mask
* fix undefined asm -> remove bic & ifdef
* fix svc asm -> ldr, #-1 and pass only character? can we remove the bic that way?