xHCI: Set link state support

This patch adds support for Set Port Feature(PORT_LINK_STATE) request.

The most significant byte (bits 15..8) of the wIndex field specifies
the U state the host software wants to put the link connected to the
port into. This request is only valid when the PORT_ENABLE bit is set
and the PORT_LINK_STATE should not be above value '5' (Rx.Detect).

This request will be later used to replace the set/clear suspend USB3
protocol ports in hub driver.

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>