of: unittest: document intentional interrupt-map provider build warning

A recently implemented dtc compiler warning reports a dts problem
via a build warning:

   drivers/of/unittest-data/tests-interrupts.dtsi:32.26-35.6: Warning (interrupt_map): /testcase-data/interrupts/intmap1: Missing '#address-cells' in interrupt-map provider

The warning will be addressed by a separate patch by suppressing the
warning for .dts files that include this .dtsi.  This patch documents
why the warning is due to a deliberately incorrect .dtsi file so that
no one will fix the .dtsi file to prevent the build warning.

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Link: https://lore.kernel.org/r/20211030011039.2106946-1-frowand.list@gmail.com
Signed-off-by: Rob Herring <robh@kernel.org>
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index c12bcb5..481ba86 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -1129,6 +1129,12 @@ static void __init of_unittest_parse_interrupts_extended(void)
 			passed &= (args.args[1] == 14);
 			break;
 		case 6:
+			/*
+			 * Tests child node that is missing property
+			 * #address-cells.  See the comments in
+			 * drivers/of/unittest-data/tests-interrupts.dtsi
+			 * nodes intmap1 and interrupts-extended0
+			 */
 			passed &= !rc;
 			passed &= (args.args_count == 1);
 			passed &= (args.args[0] == 15);