powerpc/radix: Update MMU cache

With radix there is no MMU cache. Hence we don't need to do anything in
update_mmu_cache().
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: NBalbir Singh <bsingharora@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/mem.c

@@ -499,6 +499,8 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 	 * called with either mm->page_table_lock held or ptl lock held
 	 */
 	unsigned long access = 0, trap;
+	if (radix_enabled())
+		return;
 
 	/* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
 	if (!pte_young(*ptep) || address >= TASK_SIZE)