PCI: Add PCI_EXP_LNKCTL2_TLS* macros

The Link Control 2 register is missing macros for Target Link Speeds.  Add
those in.

Change-Id: Iec2d05836975e5aee50ac6e72d8cf348fa387ae7
Signed-off-by: Frederick Lawler <fred@fredlawl.com>
[bhelgaas: use "GT" instead of "GB"]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Git-commit: c80851f6
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Tony Truong <truong@codeaurora.org>