rcutorture: Fix jitter.sh spin time

An embarrassing syntax error in jitter.sh makes for fixed spin time.
This commit therefore makes it be variable, as intended, albeit with
very coarse-grained adjustment.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2025-07-10 16:41:53 -07:00
commit e95f6ccdbc