locktorture: Add long_hold to adjust lock-hold delays

This commit adds a long_hold module parameter to allow testing diagnostics
for excessive lock-hold times.  Also adjust torture_param() invocations
for longer line length while in the area.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>