sched/rt: Try to restart rt period timer when rt runtime exceeded

hulk inclusion
category: bugfix
bugzilla: 185759 https://gitee.com/openeuler/kernel/issues/I4DDEL



---------------------------

When rt_runtime is modified from -1 to a valid control value, it may
cause the task to be throttled all the time. Operations like the following
will trigger the bug. E.g:
1. echo -1 > /proc/sys/kernel/sched_rt_runtime_us
2. Run a FIFO task named A that executes while(1)
3. echo 950000 > /proc/sys/kernel/sched_rt_runtime_us

When rt_runtime is -1, The rt period timer will not be activated when task A
enqueued. And then the task will be throttled after setting rt_runtime to
950,000. The task will always be throttled because the rt period timer is not
activated.

Signed-off-by: Li Hua <hucool.lihua@huawei.com>
Reviewed-by: Chen Hui <judy.chenhui@huawei.com>
Reviewed-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>