Currently, the torture.sh --do-kvfree testing is hard-coded to ten
minutes, ignoring the --duration argument.  This commit therefore scales
this test duration the same as for the rcutorture tests.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>