powerpc/4xx/ocm: Fix compilation error due to PAGE_KERNEL usage

This patch fixes a recent compilation regression in ocm:

  ocm.c: In function ‘ocm_init_node’:
  ocm.c:182:18: error: invalid operands to binary |
        (have ‘int’ and ‘pgprot_t’ {aka ‘struct <anonymous>’})
        _PAGE_EXEC | PAGE_KERNEL_NCG);
                   ^

  ocm.c:197:17: error: invalid operands to binary |
        (have ‘int’ and ‘pgprot_t’ {aka ‘struct <anonymous>’})
         _PAGE_EXEC | PAGE_KERNEL);
                    ^

Fixes: 56f3c141 ("powerpc/mm: properly set PAGE_KERNEL flags in ioremap()")
Cc: stable@vger.kernel.org # v4.20
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>