ASoC: WM8804 does not support sample rates below 32kHz

Reported-by: Kieran O'Leary <Kieran.O'Leary@wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Cc: stable@kernel.org