xen/privcmd: Fix mmap batch ioctl error status copy back.

Copy back of per-slot error codes is only necessary for V2. V1 does not provide
an error array, so copyback will unconditionally set the global rc to EFAULT.
Only copyback for V2.
Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/xen/privcmd.c

@@ -389,7 +389,7 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version)
 		state.err      = err_array;
 		ret = traverse_pages(m.num, sizeof(xen_pfn_t),
 				     &pagelist, mmap_return_errors_v1, &state);
-	} else
+	} else if (version == 2)
 		ret = __copy_to_user(m.err, err_array, m.num * sizeof(int));
 
 	/* If we have not had any EFAULT-like global errors then set the global