Now that we have more than one place to get the task state,
intruduce the task_state_to_char() helper function to save some code.

No functionality changed.
Signed-off-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: <cj.chengjian@huawei.com>
Cc: <huawei.libin@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1502095463-160172-3-git-send-email-xiexiuqi@huawei.comSigned-off-by: NIngo Molnar <mingo@kernel.org>