xhci: Store information about roothubs and TTs.

For upcoming patches, we need to keep information about the bandwidth
domains under the xHCI host.  Each root port is a separate primary
bandwidth domain, and each high speed hub's TT (and potentially each port
on a multi-TT hub) is a secondary bandwidth domain.

If the table were in text form, it would look a bit like this:

EP Interval	Sum of Number	Largest Max	Max Packet
		of Packets	Packet Size	Overhead
	0	   N		   mps		  overhead
...
	15	   N		   mps		  overhead

Overhead is the maximum packet overhead (for bit stuffing, CRC, protocol
overhead, etc) for all the endpoints in this interval.  Devices with
different speeds have different max packet overhead.  For example, if
there is a low speed and a full speed endpoint that both have an interval
of 3, we would use the higher overhead (the low speed overhead).  Interval
0 is a bit special, since we really just want to know the sum of the max
ESIT payloads instead of the largest max packet size.  That's stored in
the interval0_esit_payload variable.  For root ports, we also need to keep
track of the number of active TTs.

For each root port, and each TT under a root port, store some information
about the bandwidth consumption.  Dynamically allocate an array of root
port bandwidth information for the number of root ports on the xHCI host.
Each root port stores a list of TTs under the root port.  A single TT hub
only has one entry in the list, but a multi-TT hub will have an entry per
port.

When the USB core says that a USB device is a hub, create one or more
entries in the root port TT list for the hub.  When a device is deleted,
and it is a hub, search through the root port TT list and delete all
TT entries for the hub.  Keep track of which TT entry is associated with a
device under a TT.

LS/FS devices attached directly to the root port will have usb_device->tt
set to the roothub.  Ignore that, and treat it like a primary bandwidth
domain, since there isn't really a high speed bus between the roothub and
the host.

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