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>