drivers/char: suspend handling in XHCI console driver

drivers/char: suspend handling in XHCI console driver

Similar to the EHCI driver - save/restore relevant BAR and command
register, re-configure DbC on resume and stop/start timer.
On resume trigger sending anything that was queued in the meantime.
Save full BAR value, instead of just the address part, to ease restoring
on resume.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Henry Wang <Henry.Wang@arm.com>