Use the new vmem_altmap capability to enable the pmem driver to arrange
for a struct page memmap to be established in persistent memory.

[linux@roeck-us.net: mn10300: declare __pfn_to_phys() to fix build error]
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>