[POWERPC] ] Fix memset size error

The size passing to memset is wrong.

Signed-off-by Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/prom_init.c

@@ -1244,7 +1244,7 @@ static void __init prom_initialize_tce_table(void)
 			local_alloc_bottom = base;
 
 		/* It seems OF doesn't null-terminate the path :-( */
-		memset(path, 0, sizeof(path));
+		memset(path, 0, PROM_SCRATCH_SIZE);
 		/* Call OF to setup the TCE hardware */
 		if (call_prom("package-to-path", 3, 1, node,
 			      path, PROM_SCRATCH_SIZE-1) == PROM_ERROR) {