tools: gpio: add support for reporting realtime event clock to lsgpio

Add support for reporting if a line is configured to report realtime
timestamps in events.
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20201014231158.34117-3-warthog618@gmail.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

tools/gpio/lsgpio.c

@@ -65,6 +65,10 @@ struct gpio_flag flagnames[] = {
 		.name = "bias-disabled",
 		.mask = GPIO_V2_LINE_FLAG_BIAS_DISABLED,
 	},
+	{
+		.name = "clock-realtime",
+		.mask = GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME,
+	},
 };
 
 static void print_attributes(struct gpio_v2_line_info *info)