[SCSI] FC transport: Add dev_loss_tmo callbacks, and new fast_io_fail_tmo w/ callback

This patch adds the following functionality to the FC transport:

- dev_loss_tmo LLDD callback :
  Called to essentially confirm the deletion of an rport. Thus, it is
  called whenever the dev_loss_tmo fires, or when the rport is deleted
  due to other circumstances (module unload, etc).  It is expected that
  the callback will initiate the termination of any outstanding i/o on
  the rport.

- fast_io_fail_tmo and LLD callback:
  There are some cases where it may take a long while to truly determine
  device loss, but the system is in a multipathing configuration that if
  the i/o was failed quickly (faster than dev_loss_tmo), it could be
  redirected to a different path and completed sooner.

Many thanks to Mike Reed who cleaned up the initial RFC in support
of this post.

The original RFC is at:
http://marc.theaimsgroup.com/?l=linux-scsi&m=115505981027246&w=2



Signed-off-by: James Smart <James.Smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>