In Portenta-X8 machine file, comment custom u-boot machine, this will use imx8mm-evk as per MACHINEOVERRIDES settings

Author: MaxPayne86

meta-arduino-bsp/conf/machine/portenta-x8.conf

@@ -9,8 +9,8 @@ require conf/machine/imx8mm-lpddr4-evk.conf
 MACHINEOVERRIDES .= ":imx8mm-lpddr4-evk"
 
 # Override the variables you want to change here
-UBOOT_CONFIG_BASENAME = "portenta-x8"
-UBOOT_DTB_NAME = "portenta-x8.dtb"
+#UBOOT_CONFIG_BASENAME = "portenta-x8"
+#UBOOT_DTB_NAME = "portenta-x8.dtb"
 
 IMX_DEFAULT_BSP = "nxp"
 PREFERRED_PROVIDER:virtual/kernel = "linux-imx_6.6"