Add PCIe 3.0+ decoding of the LnkCtl2 Compliance Preset/De-emphasis field

Add PCIe 3.0+ decoding of the LnkCtl2 Compliance Preset/De-emphasis field

As of PCIe 3.0, the LnkCtl2 "Compliance De-emphasis" field has been
renamed to "Compliance Preset/De-emphasis", and there are several new
bit encodings for various de-emphasis and preshoot combinations.

The name of the PCI_EXP_LNKCTL2_COM_DEEMPHASIS() macro is not changed
by this commit, as it is part of the libpci API.

Reported-by: Tim CC Chen(陳志佳) <Tim.CC.Chen@wnc.com.tw>
Signed-off-by: Lennert Buytenhek <buytenh@arista.com>