Mainline: Build error in drivers/nvdimm/pmem.c due to commit 658922e57b84

From: Guenter Roeck
Date: Fri May 06 2016 - 02:12:23 EST

alpha:allmodconfig fails to build with the following error.

drivers/nvdimm/pmem.c: In function 'nd_pfn_init':
drivers/nvdimm/pmem.c:407:17: error: 'HPAGE_SIZE' undeclared

Problem is due to commit 658922e57b84 ("libnvdimm, pfn: fix memmap
reservation sizing").

HPAGE_SIZE is not defined for all architectures and was up to now not used
in driver code. All other architectures with 64 bit physical address provide the
definition, though, as far as I can see, so it may be that only alpha is affected.

Since stable is copied - this will also result in stable build errors
if applied to -stable branches.