configs: enable use of DT for all m68k boards

Enable DT usage for all m68k boards. To provide a
working single binary, the dts has been kept as embedded.

Signed-off-by: Angelo Dureghello <angelo@sysam.it>
diff --git a/configs/eb_cpu5282_defconfig b/configs/eb_cpu5282_defconfig
index 3632706..8d3106e 100644
--- a/configs/eb_cpu5282_defconfig
+++ b/configs/eb_cpu5282_defconfig
@@ -1,6 +1,7 @@
 CONFIG_M68K=y
 CONFIG_SYS_TEXT_BASE=0xFF000000
 CONFIG_TARGET_EB_CPU5282=y
+CONFIG_DEFAULT_DEVICE_TREE="eb_cpu5282"
 CONFIG_SYS_EXTRA_OPTIONS="SYS_MONITOR_BASE=0xFF000400"
 CONFIG_BOOTDELAY=5
 # CONFIG_CONSOLE_MUX is not set