NPIV vports are managed in libfc by changing their virtual link state
when the parent N_Ports internal state changes.  The vport link is only
online when the N_Port is in a ready state (logged into the fabric).

vport_state is updated as needed in this patch as well, currently the states
LINKDOWN, INITIALIZING, ACTIVE, DSIABLED, and NO_FABRIC_SUPP are used.

This also changes the fc_host port_state handling to differentiate between
LINKDOWN and OFFLINE.
Signed-off-by: NChris Leech <christopher.leech@intel.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

Adds a function to create a new VN_Port instances, which share the EM
list with the N_Port, VN_Port lookup by fabric ID when responding to a new
request (otherwise the exchange lookup from the N_Ports EM list is trusted to
return an exchange with a cached lport value for the correct VN_Port),
a pointer to a fc_vport structure for VN_Ports, and flags to indicate if an
N_Port supports NPIV and if the switch/fabric allows it.
Signed-off-by: NChris Leech <christopher.leech@intel.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>