clk: at91: sama7g5: fix parents of PDMCs' GCLK

Audio PLL can be used as parent by the GCLKs of PDMCs.

Fixes: cb783bbb ("clk: at91: sama7g5: add clock support for sama7g5")
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20220304182616.1920392-1-codrin.ciubotariu@microchip.com