of: unittest: Add separators to of_unittest_overlay_high_level()

It is hard to see the start and end of each individual test in
of_unittest_overlay_high_level().  Add visual cues in the form of
separator comments, like was done in of_unittest_overlay_notify().

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/84530100a54a1fac932008057746015e65bc4d9a.1690533838.git.geert+renesas@glider.be
Signed-off-by: Rob Herring <robh@kernel.org>

Author: geertu

drivers/of/unittest.c

@@ -3654,6 +3654,8 @@ static __init void of_unittest_overlay_high_level(void)
 
 	/* now do the normal overlay usage test */
 
+	/* ---  overlay  --- */
+
 	EXPECT_BEGIN(KERN_ERR,
 		     "OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/substation@100/status");
 	EXPECT_BEGIN(KERN_ERR,
@@ -3704,6 +3706,8 @@ static __init void of_unittest_overlay_high_level(void)
 
 	unittest(ret, "Adding overlay 'overlay' failed\n");
 
+	/* ---  overlay_bad_add_dup_node  --- */
+
 	EXPECT_BEGIN(KERN_ERR,
 		     "OF: overlay: ERROR: multiple fragments add and/or delete node /testcase-data-2/substation@100/motor-1/controller");
 	EXPECT_BEGIN(KERN_ERR,
@@ -3725,6 +3729,8 @@ static __init void of_unittest_overlay_high_level(void)
 	EXPECT_END(KERN_ERR,
 		   "OF: overlay: ERROR: multiple fragments add and/or delete node /testcase-data-2/substation@100/motor-1/controller");
 
+	/* ---  overlay_bad_add_dup_prop  --- */
+
 	EXPECT_BEGIN(KERN_ERR,
 		     "OF: overlay: ERROR: multiple fragments add and/or delete node /testcase-data-2/substation@100/motor-1/electric");
 	EXPECT_BEGIN(KERN_ERR,
@@ -3750,9 +3756,13 @@ static __init void of_unittest_overlay_high_level(void)
 	EXPECT_END(KERN_ERR,
 		   "OF: overlay: ERROR: multiple fragments add and/or delete node /testcase-data-2/substation@100/motor-1/electric");
 
+	/* ---  overlay_bad_phandle  --- */
+
 	unittest(overlay_data_apply("overlay_bad_phandle", NULL),
 		 "Adding overlay 'overlay_bad_phandle' failed\n");
 
+	/* ---  overlay_bad_symbol  --- */
+
 	EXPECT_BEGIN(KERN_ERR,
 		     "OF: changeset: apply failed: REMOVE_PROPERTY /testcase-data-2/substation@100/hvac-medium-2:name");
 	EXPECT_BEGIN(KERN_ERR,