Save/restore PCIe/PCI-X states across S3.

Save/restore PCIe/PCI-X states across S3.

This patch is backported from upstream Linux kernel.

commit b56a5a23bfecd9cac9187164a9d5f22d287c48b9
Author: Michael S. Tsirkin <mst@mellanox.co.il>
Date:   Mon Aug 21 16:22:22 2006 +0300

    PCI: Restore PCI Express capability registers after PM event

    Restore PCI Express capability registers after PM event.
    This includes maxumum MTU for PCI express and other vital data.

    Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
commit cc692a5f1e9816671b77da77c6d6c463156ba1c7
Author: Stephen Hemminger <shemminger@osdl.org>
Date:   Wed Nov 8 16:17:15 2006 -0800

    PCI: save/restore PCI-X state

    Shouldn't PCI-X state be saved/restored?  No device really needs
    this
    right now. qla24xx (fc HBA) and mthca (infiniband) don't do
    suspend,
    and sky2 resets its tweaks when links are brought up.

    Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Dexuan Cui <dexuan.cui@intel.com>