libnvdimm: Remove unused nd_region_conflict

nd_region_conflict() has been unused since 2019's
commit a3619190 ("libnvdimm/pfn: stop padding pmem namespaces to
section alignment")

Remove it, and the region_confict() helper it uses, and the associated
struct conflict_context.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://patch.msgid.link/20250220004538.84585-2-linux@treblig.org


Signed-off-by: Ira Weiny <ira.weiny@intel.com>