zdtm: Fix sleep time unwanted overflow

After sleep 0.9 there occurs sleep 0.10 which is not what
we want. Stop incrementing on 0.9
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -287,7 +287,7 @@ EOF
 		test -f $test.out && break
 		echo Waiting...
 		sleep 0.$sltime
-		[ $sltime -le 9 ] && sltime=$((sltime+1))
+		[ $sltime -lt 9 ] && sltime=$((sltime+1))
 	done
 	cat $test.out
 	cat $test.out | grep PASS || return 2