qemu-iotests: use -nographic in test case 007

A comment explains that -nographic hangs test case 007.  This is no
longer the case so add -nographic.  This makes the test suite faster and
more pleasant to run since no windows pop up.

I am not sure exactly when -nographic starting working for this case but
there is no fundamental reason why graphics are needed here.  Make sure
the serial port is not on stdio, it would conflict with the monitor.

Also remove unnecessary trailing whitespace on these lines.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Tested-by: NKevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/007

@@ -50,10 +50,9 @@ _make_test_img 1M
 
 for i in `seq 1 10`; do
     echo "savevm $i"
-    # XXX(hch): adding -nographic would be good, but hangs the test
-    $QEMU -hda $TEST_IMG -monitor stdio >/dev/null 2>&1 <<EOF     
-savevm test-$i                                                              
-quit                                                                        
+    $QEMU -nographic -hda $TEST_IMG -serial none -monitor stdio >/dev/null 2>&1 <<EOF
+savevm test-$i
+quit
 EOF
 done