sched: Mark pick_next_task_dl() and build_sched_domain() as static

pick_next_task_dl() and build_sched_domain() aren't used outside
deadline.c and topology.c.

Make them static.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/36e4cbb6210002cadae89920ae97e19e7e513008.1493281605.git.viresh.kumar@linaro.org


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