ASoC: da7219: Fix change notifications for tone generator frequency

ASoC: da7219: Fix change notifications for tone generator frequency

The tone generator frequency control just returns 0 on successful write,
not a boolean value indicating if there was a change or not.  Compare
what was written with the value that was there previously so that
notifications are generated appropriately when the value changes.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220420133437.569229-1-broonie@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>