xhci: dbc: add timestamps to DbC state changes in a new helper.

xhci: dbc: add timestamps to DbC state changes in a new helper.

The timestamp helps us track when a state changed the last time.
It allows us to detect if DbC is stuck in connected state for too long,
and can later be used to enable runtime suspend if there is no activity
for some time

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20260603091132.1110849-11-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>