Intel xhci: refactor EHCI/xHCI port switching

Make the Linux xHCI driver automatically try to switchover the EHCI ports to
xHCI when an Intel xHCI host is detected, and it also finds an Intel EHCI host.

This means we will no longer have to add Intel xHCI hosts to a quirks list when
the PCI device IDs change.  Simply continuing to add new Intel xHCI PCI device
IDs to the quirks list is not sustainable.

During suspend ports may be swicthed back to EHCI by BIOS and not properly
restored to xHCI at resume. Previously both EHCI and xHCI resume functions
switched ports back to XHCI, but it's enough to do it in xHCI only
because the hub driver doesn't start running again until after both hosts are resumed.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>