Added code to support Tx/Rx from a VF representor port.
The VF-reps use the RX/TX rings of the Trusted VF/PF.
For each VF-rep, the Trusted VF/PF driver issues a VFR_ALLOC FW cmd that
returns "cfa_code" and "cfa_action" values.
The FW sets up the filter tables in such a way that VF traffic by
default (in absence of other rules) gets punted to the parent function
i.e. either the Trusted VF or the PF.
The cfa_code value in the RX-compl informs the driver of the source VF.
For traffic being transmitted from the VF-rep, the TX BD is tagged with
a cfa_action value that informs the HW to punt it to the corresponding
VF.