data tree CHANGE switch diff merge parameters

SO that it follows general merge prototype.
diff --git a/tests/utests/data/test_diff.c b/tests/utests/data/test_diff.c
index c84ce86..2b917e7 100644
--- a/tests/utests/data/test_diff.c
+++ b/tests/utests/data/test_diff.c
@@ -472,7 +472,7 @@
     assert_string_equal(st->xml1, st->xml2);
 
     /* merge */
-    assert_int_equal(lyd_diff_merge_all(st->diff2, &st->diff1), LY_SUCCESS);
+    assert_int_equal(lyd_diff_merge_all(&st->diff1, st->diff2), LY_SUCCESS);
 
     free(st->xml);
     lyd_print_mem(&st->xml, st->diff1, LYD_XML, LYD_PRINT_WITHSIBLINGS);
@@ -565,7 +565,7 @@
     assert_string_equal(st->xml1, st->xml2);
 
     /* merge */
-    assert_int_equal(lyd_diff_merge_all(st->diff2, &st->diff1), LY_SUCCESS);
+    assert_int_equal(lyd_diff_merge_all(&st->diff1, st->diff2), LY_SUCCESS);
 
     free(st->xml);
     lyd_print_mem(&st->xml, st->diff1, LYD_XML, LYD_PRINT_WITHSIBLINGS);
@@ -653,7 +653,7 @@
     assert_string_equal(st->xml1, st->xml2);
 
     /* merge */
-    assert_int_equal(lyd_diff_merge_all(st->diff2, &st->diff1), LY_SUCCESS);
+    assert_int_equal(lyd_diff_merge_all(&st->diff1, st->diff2), LY_SUCCESS);
 
     free(st->xml);
     lyd_print_mem(&st->xml, st->diff1, LYD_XML, LYD_PRINT_WITHSIBLINGS);
@@ -736,7 +736,7 @@
     assert_string_equal(st->xml1, st->xml2);
 
     /* merge */
-    assert_int_equal(lyd_diff_merge_all(st->diff2, &st->diff1), LY_SUCCESS);
+    assert_int_equal(lyd_diff_merge_all(&st->diff1, st->diff2), LY_SUCCESS);
 
     free(st->xml);
     lyd_print_mem(&st->xml, st->diff1, LYD_XML, LYD_PRINT_WITHSIBLINGS);
@@ -812,7 +812,7 @@
     assert_string_equal(st->xml1, st->xml2);
 
     /* merge */
-    assert_int_equal(lyd_diff_merge_all(st->diff2, &st->diff1), LY_SUCCESS);
+    assert_int_equal(lyd_diff_merge_all(&st->diff1, st->diff2), LY_SUCCESS);
 
     free(st->xml);
     lyd_print_mem(&st->xml, st->diff1, LYD_XML, LYD_PRINT_WITHSIBLINGS);
@@ -890,7 +890,7 @@
     assert_string_equal(st->xml1, st->xml2);
 
     /* merge */
-    assert_int_equal(lyd_diff_merge_all(st->diff2, &st->diff1), LY_SUCCESS);
+    assert_int_equal(lyd_diff_merge_all(&st->diff1, st->diff2), LY_SUCCESS);
 
     free(st->xml);
     lyd_print_mem(&st->xml, st->diff1, LYD_XML, LYD_PRINT_WITHSIBLINGS | LYD_PRINT_WD_ALL);