bnxt_en: allow promiscuous mode for trusted VFs

Firmware previously only allowed promiscuous mode for VFs associated with
a default VLAN. It is now possible to enable promiscuous mode for a VF
having no VLAN configured provided that it is trusted. In such cases the
VF will see all packets received by the PF, irrespective of destination
MAC or VLAN.

Note, it is necessary to query firmware at the time of bnxt_promisc_ok()
instead of in bnxt_hwrm_func_qcfg() because the trusted status might be
altered by the PF after the VF has been configured. This check must now
also be deferred because the firmware call sleeps.

Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>