compat: backport PCIe register definitions

compat: backport PCIe register definitions

New DRM core in 3.6 needs these in order to detect the maximum
link speed of the underlying bus.

This backports:

	commit cdcac9cd7741af2c2b9255cbf060f772596907bb
	Author: Dave Airlie <airlied@redhat.com>
	Date:   Wed Jun 27 08:35:52 2012 +0100

	    pci_regs: define LNKSTA2 pcie cap + bits.

	    We need these for detecting the max link speed for drm drivers.

	    Acked-by: Bjorn Helgaas <bhelgass@google.com>
	    Signed-off-by: Dave Airlie <airlied@redhat.com>
[root@ozan linux-2.6]# git describe --contains cdcac9cd
v3.6-rc1~83^2~26

Trying kernel 3.5.0-030500-generic [OK]
Trying kernel 3.4.4-030404-generic [OK]
Trying kernel 3.3.7-030307-generic [OK]
Trying kernel 3.2.2-030202-generic [OK]
Trying kernel 3.1.10-030110-generic [OK]
Trying kernel 3.0.18-030018-generic [OK]
Trying kernel 2.6.39-02063904-generic [OK]
Trying kernel 2.6.38-02063808-generic [OK]
Trying kernel 2.6.37-02063706-generic [OK]
Trying kernel 2.6.36-02063604-generic [OK]
Trying kernel 2.6.35-02063512-generic [OK]
Trying kernel 2.6.34-02063410-generic [OK]
Trying kernel 2.6.33-02063305-generic [OK]
Trying kernel 2.6.32-02063255-generic [OK]
Trying kernel 2.6.31-02063113-generic [OK]
Trying kernel 2.6.30-02063010-generic [OK]
Trying kernel 2.6.29-02062906-generic [OK]
Trying kernel 2.6.28-02062810-generic [OK]
Trying kernel 2.6.27-020627-generic [OK]
Trying kernel 2.6.26-020626-generic [OK]
Trying kernel 2.6.25-020625-generic [OK]
Trying kernel 2.6.24-020624-generic [OK]

Signed-off-by: Ozan Çağlayan <ozancag@gmail.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@frijolero.org>