[SCSI] iscsi class, qla4xxx: fix sess/conn refcounting when find fns are used

This fixes a bug where the iscsi class/driver did not do a put_device
when a sess/conn device was found. This also simplifies the interface
by not having to pass in some arguments that were duplicated and did
not need to be exported.

Reported-by: Zhao Hongjiang <zhaohongjiang@huawei.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>