powerpc: Fix some missed ppc32 mm->context.id conversions

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/ppc/mm/init.c b/arch/ppc/mm/init.c
index 386e000..c9bd184 100644
--- a/arch/ppc/mm/init.c
+++ b/arch/ppc/mm/init.c
@@ -583,7 +583,7 @@
 		mm = (address < TASK_SIZE)? vma->vm_mm: &init_mm;
 		pmd = pmd_offset(pgd_offset(mm, address), address);
 		if (!pmd_none(*pmd))
-			add_hash_page(mm->context, address, pmd_val(*pmd));
+			add_hash_page(mm->context.id, address, pmd_val(*pmd));
 	}
 #endif
 }