Setting older u-boot for Allwinner H3 due to stability issues found in latest versions 2021.04 (#3036)

config/sources/families/sun8i.conf

@@ -7,6 +7,10 @@ fi
 [[ -z $CPUMIN ]] && CPUMIN=480000
 [[ -z $CPUMAX ]] && CPUMAX=1400000
 
+# some 32bit Allwinner devices are unstable at 2021.xx
+# https://armbian.atlassian.net/browse/AR-749
+BOOTBRANCH='tag:v2020.10'
+
 family_tweaks_s()
 {
 	if [[ ${BOARD} == nanopi-r1 ]]; then