sfc: Change VF mac via PF as first preference if available.

[ Upstream commit a8aed7b3

 ]

Changing a VF's mac address through the VF (rather than via the PF)
fails with EPERM because the latter part of efx_ef10_set_mac_address
attempts to change the vport mac address list as the VF.
Even with this fixed it still fails with EBUSY because the vadaptor
is still assigned on the VF - the vadaptor reassignment must be within
a section where the VF has torn down its state.

A major reason this has broken is because we have two functions that
ostensibly do the same thing - have a PF and VF cooperate to change a
VF mac address. Rather than do this, if we are changing the mac of a VF
that has a link to the PF in the same VM then simply call
sriov_set_vf_mac instead, which is a proven working function that does
that.

If there is no PF available, or that fails non-fatally, then attempt to
change the VF's mac address as we would a PF, without updating the PF's
data.

Test case:
Create a VF:
  echo 1 > /sys/class/net/<if>/device/sriov_numvfs
Set the mac address of the VF directly:
  ip link set <vf> addr 00:11:22:33:44:55
Set the MAC address of the VF via the PF:
  ip link set <pf> vf 0 mac 00:11:22:33:44:66
Without this patch the last command will fail with ENOENT.

Signed-off-by: Jonathan Cooper <jonathan.s.cooper@amd.com>
Reported-by: Íñigo Huguet <ihuguet@redhat.com>
Fixes: 910c8789

 ("set the MAC address using MC_CMD_VADAPTOR_SET_MAC")
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>