sched/idle, alpha: Switch from TS_POLLING to TIF_POLLING_NRFLAG

Standardize the idle polling indicator to TIF_POLLING_NRFLAG such that
both TIF_NEED_RESCHED and TIF_POLLING_NRFLAG are in the same word.
This will allow us, using fetch_or(), to both set NEED_RESCHED and
check for POLLING_NRFLAG in a single operation and avoid pointless
wakeups.

Changing from the non-atomic thread_info::status flags to the atomic
thread_info::flags shouldn't be a big issue since most polling state
changes were followed/preceded by a full memory barrier anyway.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Richard Henderson <rth@twiddle.net>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: 蔡正龙 <zhenglong.cai@cs2c.com.cn>
Cc: linux-alpha@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-9tfzr196gs0n2afxv0ga8pc3@git.kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>