block: qemu-iotests, removes duplicate double quotes in 039

Test 039 had $TEST_IMG with duplicate double quotes - remove duplicate.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

tests/qemu-iotests/039

@@ -54,7 +54,7 @@ echo "== Checking that image is clean on shutdown =="
 IMGOPTS="compat=1.1,lazy_refcounts=on"
 _make_test_img $size
 
-$QEMU_IO -c "write -P 0x5a 0 512" ""$TEST_IMG"" | _filter_qemu_io
+$QEMU_IO -c "write -P 0x5a 0 512" "$TEST_IMG" | _filter_qemu_io
 
 # The dirty bit must not be set
 ./qcow2.py "$TEST_IMG" dump-header | grep incompatible_features