Revert "PSCSIStorageObject EVPD unit serial emulation"

This reverts commit 70c41dd3437e0677ed769b9ee7b1855218266b1b.

* Reverted because the old behavior that allowed EVPD for pSCSI is now
  obsolete. Passing the wwn attribute to a PSCSI storage object would simply
  have no effect.
iblock/fileio/rd_mcp wwn unit serial save/restore

* Using wwn top-level attribute to storage disk objects in config
* If wwn attribute is not present in config, then a new naa unit serial will be
  generated
Whitespaces cleanup
Add TPG nexus wwn save/restore

* Small API change: the TPG.nexus property has been renamed TPG.nexus_wwn
* Using nexus_wwn top-level attribute for either TPG or Target (when the target
  does not support multiple TPG).
* If the nexus_wwn attribute is not present in config, then a new naa nexus_wwn
  will be generated on restore.
Restore PR APTPL data on StorageObject creation

* load_pr_aptpl_from_file() renamed restore_pr_aptpl()
* Removed now useless fread_pages() in utils