i40e: remove workaround for Open Firmware MAC address

Since commit b499ffb0 ("i40e: Look up MAC address in Open Firmware
or IDPROM"), we've had support for obtaining the MAC address
form Open Firmware or IDPROM.

This code relied on sending the Open Firmware address directly to the
device firmware instead of relying on our MAC/VLAN filter list. Thus,
a work around was introduced in commit b1b15df5 ("i40e: Explicitly
write platform-specific mac address after PF reset")

We refactored the Open Firmware address enablement code in the ill-named
commit 41c4c2b5

 ("i40e: allow look-up of MAC address from Open
Firmware or IDPROM")

Since this refactor, we no longer even set I40E_FLAG_PF_MAC. Further, we
don't need this work around, because we actually store the MAC address
as part of the MAC/VLAN filter hash. Thus, we will restore the address
correctly upon reset.

The refactor above failed to revert the workaround, so do that now.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>