Up to this point, VF and PF communication always originates from VF.
As a result, VF cannot be notified of any async changes, and specifically
cannot be informed of the current link state.

This introduces the bulletin board, the mechanism through which the PF
is going to communicate async notifications back to the VF. basically,
it's a well-defined structure agreed by both PF and VF which the VF would
continuously poll and into which the PF would DMA messages when needed.
[Bulletin board is actually allocated and communicated in previous patches
but never before used]

Based on the bulletin infrastructure, the VF can query its link status
and receive said async carrier changes.
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>