lvmdbusd: Correct PV lookups

lvmdbusd: Correct PV lookups

When a user does a Manager.PvCreate they can specify the block device using a
device path that may be different than what lvm reports is the device path.  For
example a user could use:

/dev/disk/by-id/wwn-0x5002538500000000 instead of /dev/sdc

In this case the pvcreate will succeed, but when we query lvm we don't find the
newly created PV. We fail because it's device path is returned as /dev/sdc.  This
change re-uses an internal lookup which can accommodate this and correctly find
the newly created PV.

Corrects https://bugzilla.redhat.com/show_bug.cgi?id=1445654