[rpi bsp] add cmdline options

[Gedare Bloom]

> MMU setup seems to be OK for me, but what I really
> dislike is duplicate of arm-cp15-start.h to RPi.
> Shared one should be used.
>
Yes if possible.

> Les problem is to use different name for
> arm_cp15_start_mmu_config_table to not clash
> with the definition in header.
>
> I think that the name arm_cp15_start_mmu_config_table
> is not part of RTEMS API so it can be changed freely
> and if original arm_cp15_start_mmu_config_table
> is not defined then incorrect use is catch
> easily.
>

Usually a BSP will define something like, raspberrypi_start_mmu_config_table.

Gedare