IMX8: switch u-boot sources to last known working commit due to upstream changes

Author: igorpecovnik

config/sources/families/imx8m.conf

@@ -24,6 +24,7 @@ case $BOARD in
 		ATFBRANCH="branch:TQM-lf_v2.10"
 		BOOTSOURCE='https://github.com/tq-systems/u-boot-tqmaxx.git' # u-boot mainlining is hard and has low-priority
 		BOOTBRANCH='branch:TQMa8-v2020.04_imx_5.4.70_2.3.0'
+		BOOTBRANCH='commit:673acba389cfe6c9e8639e8009fc9403492f5061'
 		BOOTPATCHDIR="u-boot-tqma" # could be removed when distro boot patches are integrated
 		;;
 esac