Change breakpoint_invalidate() argument to CPUState alongside.

Since all targets now assign a softmmu-only field, we can drop helpers
cpu_class_set_{do_unassigned_access,vmsd}() and device_class_set_vmsd().

Prepares for changing cpu_memory_rw_debug() argument to CPUState.

Acked-by: Max Filippov <jcmvbkbc@gmail.com> (for xtensa)
Signed-off-by: NAndreas Färber <afaerber@suse.de>