powerpc/603: Always fault when _PAGE_ACCESSED is not set

The kernel expects pte_young() to work regardless of CONFIG_SWAP.

Make sure a minor fault is taken to set _PAGE_ACCESSED when it
is not already set, regardless of the selection of CONFIG_SWAP.

Fixes: 84de6ab0 ("powerpc/603: don't handle PAGE_ACCESSED in TLB miss handlers.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a44367744de54e2315b2f1a8cbbd7f88488072e0.1602342806.git.christophe.leroy@csgroup.eu