scsi: qla2xxx: Remove two superfluous tests

Since qlt_remove_target() only calls qlt_release() if
vha->vha_tgt.qla_tgt != NULL, checking that pointer inside qlt_release()
is not necessary. This patch fixes the following Coverity complaint:

CID 188348 (#1 of 1): Dereference after null check (FORWARD_NULL)
var_deref_model: Passing null pointer &vha->vha_tgt.qla_tgt->tgt_list_entry
to list_del, which dereferences it.

Cc: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Himanshu Madhani <hmadhani@marvell.com>
Reviewed-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>