Security: Fix the comment of cap_file_mmap()

In the comment of cap_file_mmap(), replace mmap_min_addr to be dac_mmap_min_addr.
Signed-off-by: Zhitong Wang <zhitong.wangzt@alibaba-inc.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/commoncap.c

@@ -931,7 +931,7 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages)
  * @addr: address attempting to be mapped
  * @addr_only: unused
  *
- * If the process is attempting to map memory below mmap_min_addr they need
+ * If the process is attempting to map memory below dac_mmap_min_addr they need
  * CAP_SYS_RAWIO.  The other parameters to this function are unused by the
  * capability security module.  Returns 0 if this mapping should be allowed
  * -EPERM if not.