[SCSI] fcoe, libfcoe: Add support for FIP. FCoE discovery and keep-al…

…ive.

FIP is the new standard way to discover Fibre-Channel Forwarders (FCFs)
by sending solicitations and listening for advertisements from FCFs.

It also provides for keep-alives and period advertisements so that both
parties know they have connectivity.  If the FCF loses connectivity to
the storage fabric, it can send a Link Reset to inform the E_node.

This version is also compatible with pre-FIP implementations, so no
configured selection between FIP mode and non-FIP mode is required.

We wait a couple seconds after sending the initial solicitation
and then send an old-style FLOGI.  If we receive any FIP frames,
we use FIP only mode.  If the old FLOGI receives a response,
we disable FIP mode.  After every reset or link up, this
determination is repeated.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>