[SCSI] iscsi: fix manamgement task oops

from patmans@us.ibm.com and michaelc@cs.wisc.edu

Fix bugs when forcing a mgmt task to fail and allow
session recovery to cleanup the session/connection
of any running mgmt tasks. When called during
the in login state.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>