ASoC: wm8960: Let wm8960 driver configure its bit clock and frame clock

wm8960 codec driver missing configure its bit clock and frame clock for codec
master mode, so add support for it. It will calculate a appropriate frequency
dividing ratio according to the system clock, bit clock and frame clock, then
set the corresponding registers.

Signed-off-by: Zidan Wang <zidan.wang@freescale.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>