rcutorture/kvm.sh: Remove unused variable, `alldone`

The variable `alldone` is defined but not used within an awk script.
This commit therefore removes it.

Fixes:53954671 ("rcutorture: Do better bin packing")
Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

tools/testing/selftests/rcutorture/bin/kvm.sh

@@ -238,7 +238,6 @@ BEGIN {
 }
 
 END {
-	alldone = 0;
 	batch = 0;
 	nc = -1;