mm/madvise.c: make madvise_behaviour_valid() return bool

This makes the madvise_bahaviour_valid() function return bool due to
this particular function always returning the value of either one or
zero as its return value.
Signed-off-by: NNicholas Krause <xerofoify@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/madvise.c

@@ -386,7 +386,7 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
 	}
 }
 
-static int
+static bool
 madvise_behavior_valid(int behavior)
 {
 	switch (behavior) {
@@ -408,10 +408,10 @@ madvise_behavior_valid(int behavior)
 #endif
 	case MADV_DONTDUMP:
 	case MADV_DODUMP:
-		return 1;
+		return true;
 
 	default:
-		return 0;
+		return false;
 	}
 }