oem_ibm: Move the NVRAM files to the hostfw directory

This commit would :
- Move the NVRAM files from /var/ on the BMC to the hostfw directory so
  that they don't get erased during a BMC factory reset.

- To help migrate existing systems, check if the files exist in /var/,
  and if they do, move them to the hostfw destination.

- This also adds dependent services that ensure that the links being
  setup correctly in var/lib/phosphor-software-manager/hostfw/ is run
  first.

- The services to clear PHYP NVRAM are not needed anymore. Instead of
  the BMC clearing them, the hypervisor will now clear them if the
  pvm_clear_nvram bios attribute is set.

Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.com>
Change-Id: If8da88347a82d212b30c3cb6354037b62887c67c