USB: remove bogus USB_PORT_FEAT_*_SPEED symbols

This patch (as1348) removes the bogus
USB_PORT_FEAT_{HIGHSPEED,SUPERSPEED} symbols from ch11.h.  No such
features are defined by the USB spec.  (There is a PORT_LOWSPEED
feature, but the spec doesn't mention it except to say that host
software should never use it.)  The speed indicators are port
statuses, not port features.

As a temporary workaround for the xhci-hcd driver, a fictional
USB_PORT_STAT_SUPER_SPEED symbol is added.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>