ASoC: Relax restrictions on WM8962 BCLK configuration

The restrictions on configuring BCLK are overly cautious, other constraints
in the system should ensure that reconfiguration is not possible when the
device is sufficiently active to be unable to support reclocking.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>