sched: fix gcc warnings

Meelis Roos reported these warnings on sparc64:

  CC      kernel/sched.o
  In file included from kernel/sched.c:879:
  kernel/sched_debug.c: In function 'nsec_high':
  kernel/sched_debug.c:38: warning: comparison of distinct pointer types lacks a cast

the debug check in do_div() is over-eager here, because the long long
is always positive in these places. Mark this by casting them to
unsigned long long.

no change in code output:

   text    data     bss     dec     hex filename
  51471    6582     376   58429    e43d sched.o.before
  51471    6582     376   58429    e43d sched.o.after

  md5:
   7f7729c111f185bf3ccea4d542abc049  sched.o.before.asm
   7f7729c111f185bf3ccea4d542abc049  sched.o.after.asm
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/sched_debug.c

@@ -31,9 +31,9 @@
 /*
  * Ease the printing of nsec fields:
  */
-static long long nsec_high(long long nsec)
+static long long nsec_high(unsigned long long nsec)
 {
-	if (nsec < 0) {
+	if ((long long)nsec < 0) {
 		nsec = -nsec;
 		do_div(nsec, 1000000);
 		return -nsec;
@@ -43,9 +43,9 @@ static long long nsec_high(long long nsec)
 	return nsec;
 }
 
-static unsigned long nsec_low(long long nsec)
+static unsigned long nsec_low(unsigned long long nsec)
 {
-	if (nsec < 0)
+	if ((long long)nsec < 0)
 		nsec = -nsec;
 
 	return do_div(nsec, 1000000);