py: Use mp_raise_TypeError/mp_raise_ValueError helpers where possible.

Saves 168 bytes on bare-arm.
diff --git a/py/objarray.c b/py/objarray.c
index 05d28c8..21479a8 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -391,7 +391,7 @@
                     mp_obj_array_t *src_slice = MP_OBJ_TO_PTR(value);
                     if (item_sz != mp_binary_get_size('@', src_slice->typecode & TYPECODE_MASK, NULL)) {
                     compat_error:
-                        mp_raise_msg(&mp_type_ValueError, "lhs and rhs should be compatible");
+                        mp_raise_ValueError("lhs and rhs should be compatible");
                     }
                     src_len = src_slice->len;
                     src_items = src_slice->items;