efi: Correct comment on efi_memmap_alloc

Returning zero means success now.
Signed-off-by: Liu Zixian <liuzixian4@huawei.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/memmap.c

@@ -59,8 +59,7 @@ static void __init efi_memmap_free(void)
  * Depending on whether mm_init() has already been invoked or not,
  * either memblock or "normal" page allocation is used.
  *
- * Returns the physical address of the allocated memory map on
- * success, zero on failure.
+ * Returns zero on success, a negative error code on failure.
  */
 int __init efi_memmap_alloc(unsigned int num_entries,
 		struct efi_memory_map_data *data)