ASoC: atmel-classd: fix audio clock rate

Fix the audio clock rate according to the datasheet.

Reported-by: Dushara Jayasinghe <dushara@successful.com.au>
Signed-off-by: Songjun Wu <songjun.wu@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org