For this to work, we'd need to replace the present SETUP1 macro with
more macros like those used in the MIPS HAL. As per comment from
Mark, it may be a little hard to do properly: some platforms need to
init memory controller before MMU, others need to do it the other
way.

I suggest we use something like:

 hal_cpu_init
#ifdef CYGHWR_ARM_MMU_BEFORE_MEMC
 hal_mmu_init
 hal_memc_init
#else
 hal_memc_init
 hal_mmu_init
#endif
 hal_fpu_init
 hal_intc_init
 hal_cache_init
 hal_timer_init


There are already two platforms supporting ROMRAM startup using magic
in the SETUP1 macro.