octeontx2-af: Support to enable/disable default MCAM entries

For a PF/VF with a NIXLF attached has default/reserved MCAM entries
for receiving Ucast/Bcast/Promisc traffic. Ideally traffic should be
forwarded to NIXLF only after it's contexts are initialized. This
patch keeps these default entries disabled and adds mbox messages
for a PF/VF to enable these once NPA/NIXLF initialization is done.
Likewise while PF/VF is being teared down, it can send the disable
mailbox message to stop receiving traffic.

Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>