ASoC: fsl_asrc: Add an option to select internal ratio mode

The ASRC not only supports ideal ratio mode, but also supports
internal ratio mode.

For internal rato mode, the rate of clock source should be divided
with no remainder by sample rate, otherwise there is sound
distortion.

Add function fsl_asrc_select_clk() to find proper clock source for
internal ratio mode, if the clock source is available then internal
ratio mode will be selected.

With change, the ideal ratio mode is not the only option for user.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Nicolin Chen <nicoleotsuka@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/1593525367-23221-1-git-send-email-shengjiu.wang@nxp.com


Signed-off-by: Mark Brown <broonie@kernel.org>