powerpc/603: Don't worry about _PAGE_USER in TLB miss handlers

PP bits take user access into account, so no need to check _PAGE_USER
here. A DSI or ISI will be generated if needed.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>