clk: mediatek: mt7981: support alternative compatible for fixed-plls

Support alternative compatible for fixed-plls clocks used upstream with
the compatible mediatek,mt7981-apmixedsys.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
diff --git a/drivers/clk/mediatek/clk-mt7981.c b/drivers/clk/mediatek/clk-mt7981.c
index 7fcb814..13dc3df 100644
--- a/drivers/clk/mediatek/clk-mt7981.c
+++ b/drivers/clk/mediatek/clk-mt7981.c
@@ -543,6 +543,7 @@
 
 static const struct udevice_id mt7981_fixed_pll_compat[] = {
 	{ .compatible = "mediatek,mt7981-fixed-plls" },
+	{ .compatible = "mediatek,mt7981-apmixedsys" },
 	{}
 };