thunderbolt: Add USB3 bandwidth management

USB3 supports both isochronous and non-isochronous traffic. The former
requires guaranteed bandwidth and can take up to 90% of the total
bandwidth. With USB4 USB3 is tunneled over USB4 fabric which means that
we need to make sure there is enough bandwidth allocated for the USB3
tunnels in addition to DisplayPort tunnels.

Whereas DisplayPort bandwidth management is static and done before the
DP tunnel is established, the USB3 bandwidth management is dynamic and
allows increasing and decreasing the allocated bandwidth according to
what is currently consumed. This is done through host router USB3
downstream adapter registers.

This adds USB3 bandwidth management to the software connection manager
so that we always try to allocate maximum bandwidth for DP tunnels and
what is left is allocated for USB3.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>