selftests: ktap_helpers: Add helper to print diagnostic messages

Similar to the C counterpart, add a helper to print a diagnostic
message.
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/kselftest/ktap_helpers.sh

@@ -19,6 +19,11 @@ ktap_print_header() {
 	echo "TAP version 13"
 }
 
+ktap_print_msg()
+{
+	echo "#" $@
+}
+
 ktap_set_plan() {
 	num_tests="$1"