USB: Add SuperSpeed to the list of USB device speeds.

Modify the USB core to handle the new USB 3.0 speed, "SuperSpeed".  This
is 5.0 Gbps (wire speed).  There are probably more places that check for
speed that I've missed.

SuperSpeed devices have a 512 byte endpoint 0 max packet size.  This shows
up as a bMaxPacketSize0 set to 0x09 (see table 9-8 of the USB 3.0 bus
spec).

xHCI spec says that the xHC can handle intervals up to 2^15 microframes.  That
might change when real silicon becomes available.

Add FIXME note for SuperSpeed isochronous endpoints.  They can transmit up
to 16 packets in one "burst" before they wait for an acknowledgment of the
packets.  They can do up to 3 bursts per microframe (determined by the
mult value in the endpoint companion descriptor).  The xHCI driver doesn't
have support for isoc yet, so fix this later.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>