counter: add new COUNTER_EVENT_CHANGE_OF_STATE

Add new counter event to notify user space about every new counter
pulse.

Link: https://lore.kernel.org/r/20220203135727.2374052-2-o.rempel@pengutronix.deSigned-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/486a5de67414470449efb84d06a2f2214f4bb31d.1647373009.git.vilhelm.gray@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/uapi/linux/counter.h

@@ -61,6 +61,8 @@ enum counter_event_type {
 	COUNTER_EVENT_THRESHOLD,
 	/* Index signal detected */
 	COUNTER_EVENT_INDEX,
+	/* State of counter is changed */
+	COUNTER_EVENT_CHANGE_OF_STATE,
 };
 
 /**