[SCSI] libfc: fix: cancel rport retry timer

The timer for rport retries wasn't getting canceled, and
would occasionally go off after the module was unloaded.

Add logic to cancel the timer in fc_rport_work().

Since we cancel the timer before deleting the rdata,
it is no longer necessary to do a get_device() for the pending timer.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>