powerpc/pseries: Switch pseries drivers to use machine_xxx_initcall()

powerpc/pseries: Switch pseries drivers to use machine_xxx_initcall()

A lot of the code in platforms/pseries is using non-machine initcalls.
That means if a kernel built with pseries support runs on another
platform, for example powernv, the initcalls will still run.

Most of these cases are OK, though sometimes only due to luck. Some were
having more effect:

 * hcall_inst_init
  - Checking FW_FEATURE_LPAR which is set on ps3 & celleb.
 * mobility_sysfs_init
  - created sysfs files unconditionally
  - but no effect due to ENOSYS from rtas_ibm_suspend_me()
 * apo_pm_init
  - created sysfs, allows write
  - nothing checks the value written to though
 * alloc_dispatch_log_kmem_cache
  - creating kmem_cache on non-pseries machines

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>