sched/deadline: Fix sparse static warnings

new sparse warnings:

  >> kernel/sched/cpudeadline.c:38:6: sparse: symbol 'cpudl_exchange' was not declared. Should it be static?
  >> kernel/sched/cpudeadline.c:46:6: sparse: symbol 'cpudl_heapify' was not declared. Should it be static?
  >> kernel/sched/cpudeadline.c:71:6: sparse: symbol 'cpudl_change_key' was not declared. Should it be static?
  >> kernel/sched/cpudeadline.c:195:15: sparse: memset with byte count of 163928

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Fixes: 6bfd6d72f51c ("sched/deadline: speed up SCHED_DEADLINE pushes with a push-heap")
Link: http://lkml.kernel.org/r/52d47f8c.EYJsA5+mELPBk4t6\%fengguang.wu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/cpudeadline.c

@@ -35,7 +35,7 @@ static inline int dl_time_before(u64 a, u64 b)
 	return (s64)(a - b) < 0;
 }
 
-void cpudl_exchange(struct cpudl *cp, int a, int b)
+static void cpudl_exchange(struct cpudl *cp, int a, int b)
 {
 	int cpu_a = cp->elements[a].cpu, cpu_b = cp->elements[b].cpu;
 
@@ -43,7 +43,7 @@ void cpudl_exchange(struct cpudl *cp, int a, int b)
 	swap(cp->cpu_to_idx[cpu_a], cp->cpu_to_idx[cpu_b]);
 }
 
-void cpudl_heapify(struct cpudl *cp, int idx)
+static void cpudl_heapify(struct cpudl *cp, int idx)
 {
 	int l, r, largest;
 
@@ -68,7 +68,7 @@ void cpudl_heapify(struct cpudl *cp, int idx)
 	}
 }
 
-void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
+static void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
 {
 	WARN_ON(idx > num_present_cpus() || idx == IDX_INVALID);