In some cases, it is possible that the follower shares a clock with the
driver, but the driver rate is not known when the follower is assigned
to the driver. If this happens, then state->driver_rate is 0, and when
setting the format, we might think that we need to resample (because
follower rate != driver rate). This can cause us to incorrectly halve
the period size for the node.
This was introduced in commit 0b67c10a9c,
which forces reevaluation of matching status on driver change.
To avoid this, let us also probe for the driver rate when updating the
matching status, so we can make the update more accurate.
019b53ace8