PM / Hibernate: Return error code when alloc_image_page() fails

Currently we return 0 in swsusp_alloc() when alloc_image_page() fails.
Fix that.  Also remove unneeded "error" variable since the only
useful value of error is -ENOMEM.

[rjw: Fixed up the changelog and changed subject.]
Signed-off-by: NStanislaw Gruszka <stf_xl@wp.pl>
Cc: stable@kernel.org
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

kernel/power/snapshot.c

@@ -1519,11 +1519,8 @@ static int
 swsusp_alloc(struct memory_bitmap *orig_bm, struct memory_bitmap *copy_bm,
 		unsigned int nr_pages, unsigned int nr_highmem)
 {
-	int error = 0;
-
 	if (nr_highmem > 0) {
-		error = get_highmem_buffer(PG_ANY);
-		if (error)
+		if (get_highmem_buffer(PG_ANY))
 			goto err_out;
 		if (nr_highmem > alloc_highmem) {
 			nr_highmem -= alloc_highmem;
@@ -1546,7 +1543,7 @@ swsusp_alloc(struct memory_bitmap *orig_bm, struct memory_bitmap *copy_bm,
 
  err_out:
 	swsusp_free();
-	return error;
+	return -ENOMEM;
 }
 
 asmlinkage int swsusp_save(void)