thunderbolt: Add wake on connect/disconnect on USB4 ports

Wake on connect/disconnect is only supported while runtime suspend for
now, which is obviously necessary. It is also not inherently desired for
the system to wakeup on Thunderbolt/USB4 hot plug events. However, we
can still make user in control of waking up the system in the events of
hot plug/unplug.

This patch adds 'wakeup' attribute under 'usb4_portX/power' sysfs
attribute and only enables wakes on connect/disconnect to the respective
port when 'wakeup' is set to 'enabled'. The attribute is set to
'disabled' by default.

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