Add support of two Audio PLL source

Merge series from Shengjiu Wang <shengjiu.wang@nxp.com>:

i.MX8MQ/MN/MM/MP platforms typically have 2 AUDIO PLLs being
configured to handle 8kHz and 11kHz series audio rates.

The patches implement the functionality to select at runtime
the appropriate AUDIO PLL for root clock, if there is no
two PLL registered, then no action taken.