[SCSI] libfc: Remove usage of the Scsi_Host's host_lock

This patch removes the use of the Scsi_Host's host_lock
within fc_queuecommand. It also removes the DEF_SCSI_QCMD
usage so that libfc has fully moved on to the new
queuecommand interface.

Signed-off-by: Robert Love <robert.w.love@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Reviewed-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>