gpio: uapi: clarify hte references

The full name of the HTE subsystem is "hardware timestamping engine",
so correct references and highlight that this refers to the HTE
subsystem.

Extend the description of struct gpio_v2_line_event to clarify that
the timestamp_ns is sourced from the HTE if the
GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE is set.
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

include/uapi/linux/gpio.h

@@ -67,7 +67,7 @@ struct gpiochip_info {
  * @GPIO_V2_LINE_FLAG_BIAS_DISABLED: line has bias disabled
  * @GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME: line events contain REALTIME timestamps
  * @GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE: line events contain timestamps from
- * hardware timestamp engine
+ * the hardware timestamping engine (HTE) subsystem
  */
 enum gpio_v2_line_flag {
 	GPIO_V2_LINE_FLAG_USED			= _BITULL(0),
@@ -288,6 +288,10 @@ enum gpio_v2_line_event_id {
  *
  * If the %GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME flag is set then the
  * @timestamp_ns is read from %CLOCK_REALTIME.
+ *
+ * If the %GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE flag is set then the
+ * @timestamp_ns is provided by the hardware timestamping engine (HTE)
+ * subsystem.
  */
 struct gpio_v2_line_event {
 	__aligned_u64 timestamp_ns;