clk: at91: sam9x60: Don't use audio PLL

On sam9x60, there is not audio PLL and so I2S and classD have to use one
of the best matching parents for their generated clock.

Fixes: 01e2113d ("clk: at91: add sam9x60 pmc driver")
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Link: https://lkml.kernel.org/r/20200131115816.12483-1-codrin.ciubotariu@microchip.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>