build: honor V=1 when flashing via DFU

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/scripts/support/dfuutil.sh b/scripts/support/dfuutil.sh
index 4cec9db..526356c 100755
--- a/scripts/support/dfuutil.sh
+++ b/scripts/support/dfuutil.sh
@@ -71,6 +71,11 @@
     return $ok
 }
 
+if [ "$KBUILD_VERBOSE" -eq 1 ]
+then
+        set -x
+fi
+
 CMD=$1
 shift