[PATCH] ppc64: fix mount compat translation bug

From Dave Miller:

We weren't handling a NULL 'type' argument to mount() properly,
f.e. this happens legitimately when changing the options of an
existing mount.

arch/ppc64/kernel/sys_ppc32.c

@@ -405,14 +405,13 @@ asmlinkage long sys32_mount(char *dev_name, char *dir_name, char *type, unsigned
 	if (err)
 		goto out;
 
-	if (!type_page) {
-		err = -EINVAL;
-		goto out;
+	if (type_page) {
+		is_smb = !strcmp((char *)type_page, SMBFS_NAME);
+		is_ncp = !strcmp((char *)type_page, NCPFS_NAME);
+	} else {
+		is_smb = is_ncp = 0;
 	}
 
-	is_smb = !strcmp((char *)type_page, SMBFS_NAME);
-	is_ncp = !strcmp((char *)type_page, NCPFS_NAME);
-
 	err = copy_mount_stuff_to_kernel((const void *)AA(data), &data_page);
 	if (err)
 		goto type_out;