MFC r255768:
Stability fixes for Intel LynxPoint XHCI controllers. Disable XHCI port
routing if we get certain errors. Poll for command completion upon
command timeouts. The XHCI error events might not generate interrupts.

PR:		usb/181159
MFC r255712:
 Remove extra 'MAKE_FLAGS' line.
Merge remote-tracking branch 'upstream-github/stable/9' into stable/9