csky: add support for TIF_NOTIFY_SIGNAL

[ Upstream commit f3924d76 ]

Wire up TIF_NOTIFY_SIGNAL handling for csky.

Cc: linux-csky@vger.kernel.org
Acked-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>