ASoC: fsl_asrc: Move common definition to fsl_asrc_common

There is a new ASRC included in i.MX serial platform, there
are some common definition can be shared with each other.
So move the common definition to a separate header file.

And add fsl_asrc_pair_priv and fsl_asrc_priv for
the variable specific for the module, which can be used
internally.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Link: https://lore.kernel.org/r/7106993928ea9e9720e6b42ec601871103155b1c.1587038908.git.shengjiu.wang@nxp.com


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