block: add clock_type field to ThrottleGroup

Clock type in throttling is currently inferred by the ThrottleTimer's
clock type even though it is a per-ThrottleGroup property; it doesn't
make sense to have different clock types in the same group. Moving this
to a field in ThrottleGroup can simplify some of the throttle functions.

Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

include/qemu/throttle.h

@@ -139,6 +139,7 @@ bool throttle_enabled(ThrottleConfig *cfg);
 bool throttle_is_valid(ThrottleConfig *cfg, Error **errp);
 
 void throttle_config(ThrottleState *ts,
+                     QEMUClockType clock_type,
                      ThrottleTimers *tt,
                      ThrottleConfig *cfg);