mx6cuboxi: fixup dtb ethernet phy nodes before booting an OS

SoM revision 1.9 has replaced the ar8035 phy address 0 with an adin1300
at address 1. Because early SoMs had a hardware flaw, the ar8035 can
also appear at address 4 - making it a total of 3 phy nodes in the DTB.

To avoid confusing Linux with probe errors, fixup the dtb to only enable
the phy node that is detected at runtime.

Signed-off-by: Josua Mayer <josua@solid-run.com>
diff --git a/configs/mx6cuboxi_defconfig b/configs/mx6cuboxi_defconfig
index 1e2e332..d3ac8ee 100644
--- a/configs/mx6cuboxi_defconfig
+++ b/configs/mx6cuboxi_defconfig
@@ -22,6 +22,7 @@
 CONFIG_AHCI=y
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT=y
+CONFIG_OF_BOARD_SETUP=y
 CONFIG_BOOTCOMMAND="run findfdt; run finduuid; run distro_bootcmd"
 CONFIG_USE_PREBOOT=y
 CONFIG_PREBOOT="if hdmidet; then usb start; setenv stdin  serial,usbkbd; setenv stdout serial,vidconsole; setenv stderr serial,vidconsole; else setenv stdin  serial; setenv stdout serial; setenv stderr serial; fi;"