MFC r261414, r261415, r261417, r261418, r261419

Don't call device_set_ivars() for the mmchs

Change the way pcpu and curthread are stored per-core

Invalidate cachelines for bounce pages on PREREAD too, there may still be
stale entries from a previous transfer.

Only use the CPU ID register if SMP is defined. Some non-MPCore armv6 cpu,
such as the one found in the RPi, don't have it, and just hang when we try
to access it.

MFC r261410

Follow r261352 by updating all drivers which are children of simplebus
to check the status property in their probe routines.

MFC r257199, r257200, r257217:

Remove all #include <machine/pmap.h> from arm code. It's already
included by vm/pmap.h, which is a prerequisite for arm/machine/pmap.h
so there's no reason to ever include it directly.

Remove #include <machine/frame.h> from all the arm code that doesn't
really need it. That would be almost everywhere it was included. Add
it in a couple files that really do need it and were previously getting
it by accident via another header.

Remove the last dregs of trapframe_t. It turns out only arm was using
this type, so remove it to make arm code more consistant with other
platforms.

MFC r261414, r261415, r261417, r261418, r261419

Don't call device_set_ivars() for the mmchs

Change the way pcpu and curthread are stored per-core

Invalidate cachelines for bounce pages on PREREAD too, there may still be
stale entries from a previous transfer.

Only use the CPU ID register if SMP is defined. Some non-MPCore armv6 cpu,
such as the one found in the RPi, don't have it, and just hang when we try
to access it.

MFC r261410

Follow r261352 by updating all drivers which are children of simplebus
to check the status property in their probe routines.

MFC r257199, r257200, r257217:

Remove all #include <machine/pmap.h> from arm code. It's already
included by vm/pmap.h, which is a prerequisite for arm/machine/pmap.h
so there's no reason to ever include it directly.

Remove #include <machine/frame.h> from all the arm code that doesn't
really need it. That would be almost everywhere it was included. Add
it in a couple files that really do need it and were previously getting
it by accident via another header.

Remove the last dregs of trapframe_t. It turns out only arm was using
this type, so remove it to make arm code more consistant with other
platforms.