arm64: define TIF_POLLING_NRFLAG

arm64: define TIF_POLLING_NRFLAG

Commit 842514849a61 ("arm64: Remove TIF_POLLING_NRFLAG") had removed
TIF_POLLING_NRFLAG because arm64 only supported non-polled idling via
cpu_do_idle().

To add support for polling via cpuidle-haltpoll, we want to use the
standard poll_idle() interface, which sets TIF_POLLING_NRFLAG while
polling.

Reuse the same bit to define TIF_POLLING_NRFLAG.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Tested-by: Misono Tomohiro <misono.tomohiro@fujitsu.com>