ppc64: Add a missing isync in __hash_page, alloc hash table on PowerMac G5

arch/ppc64/mm/hash_low.S

@@ -95,7 +95,7 @@ _GLOBAL(__hash_page)
 	/* Write the linux PTE atomically (setting busy) */
 	stdcx.	r30,0,r6
 	bne-	1b
-	
+	isync
 
 	/* Step 2:
 	 *

arch/ppc64/mm/hash_utils.c

@@ -140,7 +140,8 @@ void __init htab_initialize(void)
 	htab_data.htab_num_ptegs = pteg_count;
 	htab_data.htab_hash_mask = pteg_count - 1;
 
-	if (systemcfg->platform == PLATFORM_PSERIES) {
+	if (systemcfg->platform == PLATFORM_PSERIES ||
+	    systemcfg->platform == PLATFORM_POWERMAC) {
 		/* Find storage for the HPT.  Must be contiguous in
 		 * the absolute address space.
 		 */