ASoC: wm8960: update pll and clock setting function

Add sysclk auto mode. When it's sysclk auto mode, if the MCLK is
available for clock configure, using MCLK to provide sysclk directly,
otherwise, search a available pll out frequcncy and set pll.

Configure clock in hw_params may cause problems when using bypass style
paths without hw_params in machine driver getting called. So add configure
clock to set_bias_level.

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>