rcutorture's module parameters currently use permissions of 0, so they
don't show up in /sys/module/rcutorture/parameters.  Change the permissions
on all module parameters to world-readable (0444).

rcutorture does all of its initialization and thread startup when loaded
and relies on the parameters not changing during execution, so they should
not permit writing.  However, reading seems fine.
Signed-off-by: Josh Triplett <josh@freedesktop.org>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>