gpiolib: cdev: Fix kernel doc for struct line

Kernel doc validator is not happy:
  gpiolib-cdev.c:487: warning: Function parameter or member 'hdesc' not described in 'line'
  gpiolib-cdev.c:487: warning: Function parameter or member 'raw_level' not described in 'line'
  gpiolib-cdev.c:487: warning: Function parameter or member 'total_discard_seq' not described in 'line'
  gpiolib-cdev.c:487: warning: Function parameter or member 'last_seqno' not described in 'line'

Describe above mentioned parameters.

Fixes: 2068339a ("gpiolib: cdev: Add hardware timestamp clock type")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Dipen Patel <dipenp@nvidia.com>
Acked-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpio/gpiolib-cdev.c

@@ -421,6 +421,10 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
  * @work: the worker that implements software debouncing
  * @sw_debounced: flag indicating if the software debouncer is active
  * @level: the current debounced physical level of the line
+ * @hdesc: the Hardware Timestamp Engine (HTE) descriptor
+ * @raw_level: the line level at the time of event
+ * @total_discard_seq: the running counter of the discarded events
+ * @last_seqno: the last sequence number before debounce period expires
  */
 struct line {
 	struct gpio_desc *desc;