test: dfu: cleanup before execution

Call cleanup() before running tests too. If a previous test was CTRL-C'd
some stale files may have been left around. dfu-util refuses to receive
a file to a filename that already exists, which results in false test
failures if the files aren't cleaned up first.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

test/dfu/dfu_gadget_test.sh

@@ -66,6 +66,7 @@ printf "$COLOUR_GREEN===========================================================
 echo "DFU EP0 transmission test program"
 echo "Trouble shoot -> disable DBG (even the KERN_DEBUG) in the UDC driver"
 echo "@ -> TRATS2 # dfu 0 mmc 0"
+cleanup
 mkdir -p $DIR$RCV_DIR
 touch $LOG_FILE