drm/i915/buddy: tidy up i915_buddy_fini

If we are leaking nodes don't hide it. Also stop trying to be
"defensive" and instead embrace Kasan et al.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816105357.14340-1-matthew.auld@intel.com

drivers/gpu/drm/i915/i915_buddy.c

@@ -171,15 +171,10 @@ int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 chunk_size)
 
 void i915_buddy_fini(struct i915_buddy_mm *mm)
 {
-	int err = 0;
 	int i;
 
 	for (i = 0; i < mm->n_roots; ++i) {
-		if (!i915_buddy_block_is_free(mm->roots[i])) {
-			err = -EBUSY;
-			continue;
-		}
-
+		GEM_WARN_ON(!i915_buddy_block_is_free(mm->roots[i]));
 		i915_block_free(mm->roots[i]);
 	}