oem: ibm: Add services to reset PHYP NVRAM

Create new services that delete the PHYP NVRAM files and re-create them
to be used by the bios factory reset method since it needs to clear all
host-related data as part of the reset.

Tested: Verified the PHYP NVRAM files were deleted and recreated:

root@p10bmc:~# ls -l /var/lib/pldm/PHYP-NVRAM*
-rw-r--r--    1 root     root     148897792 Aug 16 16:07
/var/lib/pldm/PHYP-NVRAM

root@p10bmc:~# systemctl start pldm-reset-phyp-nvram.service
Aug 16 18:55:53 p10bmc systemd[1]: Starting Reset PHYP-NVRAM file...
Aug 16 18:55:53 p10bmc systemd[1]: pldm-reset-phyp-nvram.service:
Deactivated successfully.
Aug 16 18:55:53 p10bmc systemd[1]: Finished Reset PHYP-NVRAM file.
Aug 16 18:55:53 p10bmc systemd[1]: Starting Create empty PHYP-NVRAM
file...
systemctl start Aug 16 18:55:54 p10bmc dd[622]: 145408+0 records in
Aug 16 18:55:54 p10bmc dd[622]: 145408+0 records out
Aug 16 18:55:54 p10bmc systemd[1]: pldm-create-phyp-nvram.service:
Deactivated successfully.
Aug 16 18:55:54 p10bmc systemd[1]: Finished Create empty PHYP-NVRAM
file.

root@p10bmc:~# ls -l /var/lib/pldm/PHYP-NVRAM*
-rw-r--r--    1 root     root     148897792 Aug 16 18:55
/var/lib/pldm/PHYP-NVRAM

Change-Id: Ice10ff48d32f89447ed66434fa9c3f56f9535a37
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/oem/ibm/service_files/pldm-reset-phyp-nvram-cksum.service b/oem/ibm/service_files/pldm-reset-phyp-nvram-cksum.service
new file mode 100644
index 0000000..5b8d2fd
--- /dev/null
+++ b/oem/ibm/service_files/pldm-reset-phyp-nvram-cksum.service
@@ -0,0 +1,9 @@
+[Unit]
+Description=Reset PHYP-NVRAM-CKSUM file
+Requires=pldm-create-phyp-nvram-cksum.service
+Before=pldm-create-phyp-nvram-cksum.service
+
+[Service]
+ExecStart=/bin/rm -f /var/lib/pldm/PHYP-NVRAM-CKSUM
+Type=oneshot
+RemainAfterExit=no