be2net: Provide an alternate way to read pf_num for BEx chips

The driver gets the pf_num for Skyhawk and Lancer using
GET_FUNC_CONFIG FW command. But since that command is not
supported in BEx, we need to get it from some other command.
Otherwise TPE recovery would fail since all NIC PFs would
end up with a func num of 0. There's a pci function number
field in the response  of GET_CNTL_ATTRIBUTES command that
can be read to get the same info for BEx adapters.

Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>