FRV: __pte_to_swp_entry doesn't expand correctly

The macro doesn't expand correctly when its parameter isn't 'pte'.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>