[POWERPC] 8xx: platform specific mmu updates

This is just a straight port of the same done in arch/ppc
by Marcelo Tosatti. One used to be
[PATCH] ppc32 8xx: update_mmu_cache() needs unconditional tlbie,
commit eb07d964

In a nutshell, the board is nearly stuck without this, yet without any
visible failure - being just very slow.
Signed-off-by: Vitaly Bordug <vbordug@ru.mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/mm/mem.c

@@ -490,9 +490,6 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 	    !cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 	    pfn_valid(pfn)) {
 		struct page *page = pfn_to_page(pfn);
-		if (!PageReserved(page)
-		    && !test_bit(PG_arch_1, &page->flags)) {
-			if (vma->vm_mm == current->active_mm) {
 #ifdef CONFIG_8xx
 		/* On 8xx, cache control instructions (particularly
 		 * "dcbst" from flush_dcache_icache) fault as write
@@ -503,6 +500,9 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 		 */
 		_tlbie(address);
 #endif
+		if (!PageReserved(page)
+		    && !test_bit(PG_arch_1, &page->flags)) {
+			if (vma->vm_mm == current->active_mm) {
 				__flush_dcache_icache((void *) address);
 			} else
 				flush_dcache_icache_page(page);