Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using the yet-unused bit
31.

Link: https://lkml.kernel.org/r/20230113171026.582290-15-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>