sfc: detect ef100 MAE admin privilege/capability at probe time

One PCIe function per network port (more precisely, per m-port group) is
 responsible for configuring the Match-Action Engine which performs
 switching and packet modification in the slice to support flower/OVS
 offload.  The GRP_MAE bit in the privilege mask indicates whether a
 given function has this capability.
At probe time, call MCDIs to read the calling function's privilege mask,
 and store the GRP_MAE bit in a new ef100_nic_data member.

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>