Link: https://git.alpinelinux.org/aports/tree/testing/linux-elm?h=master

--- a/arch/arm64/boot/dts/mediatek/mt8173.dtsi	2020-12-13 22:41:30.000000000 +0000
+++ a/arch/arm64/boot/dts/mediatek/mt8173.dtsi	2021-01-06 19:57:33.225047779 +0000
@@ -55,6 +55,9 @@
 		serial1 = &uart1;
 		serial2 = &uart2;
 		serial3 = &uart3;
+		mmc0 = &mmc0;
+		mmc1 = &mmc1;
+		mmc2 = &mmc2;
 	};
 
 	cluster0_opp: opp_table0 {
