fbnic: Do not consider mailbox "initialized" until we have verified fw version

In order for us to make use of the information in the PHY we need to verify
that the FW capabilities message has been processed. To do so we should
poll until the FW version in the capabilities message is at least at the
minimum level needed to verify that the FW can support the basic PHY config
messages.

As such this change adds logic so that we will poll the mailbox until such
time as the FW version can be populated with an acceptable value. If it
doesn't reach a sufficicient value the mailbox will be considered to have
timed out.

Signed-off-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://patch.msgid.link/175028444873.625704.10269838393153693403.stgit@ahduyck-xeon-server.home.arpa


Signed-off-by: Paolo Abeni <pabeni@redhat.com>