[bug]Fix namespace section padding relative to other regions

[quanxian]

Description:

Commit cfe30b872058 "libnvdimm, pmem: adjust for section collisions with
'System RAM'" enabled the libnvdimm core to workaround occasions where
platform firmware arranges for "System RAM" and "Persistent Memory" to
collide within a single section boundary. Unfortunately, as reported in
this issue [1], platform firmware can inflict the same collision between
persistent memory regions.

The approach of interrogating iomem_resource does not work in this
case because platform firmware may merge multiple regions into a single
iomem_resource range. Instead provide a method to interrogate regions
that share the same parent bus.

This is a stop-gap until the core-MM can grow support for hotplug on
sub-section boundaries.

[1]: https://github.com/pmem/ndctl/issues/76

Commits:
ae86cbfef381 libnvdimm, pfn: Pad pfn namespaces relative to other regions
e3f5df762d4a tools/testing/nvdimm: Align test resources to 128M

Target Release: 19.04
Target Kernel: 5.0

[quanxian (quanxian-wang)]

should have been into 5.0 kernel

[quanxian (quanxian-wang)]

ae86cbfef381 e3f5df762d4a