scsi: lpfc: Fix Fabric hostname registration if system hostname changes

scsi: lpfc: Fix Fabric hostname registration if system hostname changes

There are reports of multiple ports on the same system displaying different
hostnames in fabric FDMI displays.

Currently, the driver registers the hostname at initialization and obtains
the hostname via init_utsname()->nodename queried at the time the FC link
comes up. Unfortunately, if the machine hostname is updated after
initialization, such as via DHCP or admin command, the value registered
initially will be incorrect.

Fix by having the driver save the hostname that was registered with FDMI.
The driver then runs a heartbeat action that will check the hostname.  If
the name changes, reregister the FMDI data.

The hostname is used in RSNN_NN, FDMI RPA and FDMI RHBA.

Link: https://lore.kernel.org/r/20191218235808.31922-5-jsmart2021@gmail.com
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>