x86/iommu/intel: Fix identity mapping for sandy bridge

x86/iommu/intel: Fix identity mapping for sandy bridge

With SandyBridge, Intel has changed these Socket PCI devices to
have a class type of "System Peripheral" & "Performance
counter", rather than "HostBridge".

So instead of using a "special" case to detect which devices will
not be doing DMA, use the fact that a device that is not associated
with an IOMMU, will not need an identity map.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Mike Habeck <habeck@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Daniel Rahn <drahn@suse.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-018fywmjs3lmzfyzjlktg8dx@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>