cpu_set() is marked as obsolete cpumask function and we plan to
remove it in future.

This patch replace it with modern cpumask function.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Colin Cross <ccross@android.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-tegra@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Colin Cross <ccross@android.com>