[SCSI] be2iscsi: fix null ptr ref in conn get param

The ep_disconnect function could be freeing the ep
while beiscsi_conn_get_param is running. This has
the driver use the get ep param callback instead
of the get conn param to fix this.

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