Merge branch 'for-5.1/libnvdimm' into libnvdimm-for-next

Merge miscellaneous libnvdimm sub-system updates for v5.1. Highlights
include:

* Support for the Hyper-V family of device-specific-methods (DSMs)
* Several fixes and workarounds for Hyper-V compatibility.
* Fix for the support to cache the dirty-shutdown-count at init.