ASoC: wm8994: Ensure there are enough BCLKs for four channels

commit b8edf3e5522735c8ce78b81845f7a1a2d4a08626 upstream.

Otherwise if someone tries to use all four channels on AIF1 with the
device in master mode we won't be able to clock out all the data.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>