[SCSI] ibmvfc: prep for fc host dev loss tmo support

This removes the driver's get_host_def_dev_loss_tmo
callback and just has the driver set the dev loss
using the fc class fc_host_dev_loss_tmo macro like is
done for other fc params.

This patch also removes the module dev loss param.
To override the value the fc host sysfs value being
added in the fc class patch can be used instead of the driver
module param.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>