iommu/amd: Correct the wrong setting of alias DTE in do_attach

In below commit alias DTE is set when its peripheral is
setting DTE. However there's a code bug here to wrongly
set the alias DTE, correct it in this patch.

commit e25bfb56
Author: Joerg Roedel <jroedel@suse.de>
Date:   Tue Oct 20 17:33:38 2015 +0200

    iommu/amd: Set alias DTE in do_attach/do_detach

Signed-off-by: Baoquan He <bhe@redhat.com>
Tested-by: Mark Hounschell <markh@compro.net>
Cc: stable@vger.kernel.org # v4.4
Signed-off-by: Joerg Roedel <jroedel@suse.de>