Input: MT - document new 'flags' argument of input_mt_init_slots()

Fixes new kernel-doc warning in input-mt.c:

Warning(drivers/input/input-mt.c:38): No description found for parameter
'flags'
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/input-mt.c

@@ -26,10 +26,14 @@ static void copy_abs(struct input_dev *dev, unsigned int dst, unsigned int src)
  * input_mt_init_slots() - initialize MT input slots
  * @dev: input device supporting MT events and finger tracking
  * @num_slots: number of slots used by the device
+ * @flags: mt tasks to handle in core
  *
  * This function allocates all necessary memory for MT slot handling
  * in the input device, prepares the ABS_MT_SLOT and
  * ABS_MT_TRACKING_ID events for use and sets up appropriate buffers.
+ * Depending on the flags set, it also performs pointer emulation and
+ * frame synchronization.
+ *
  * May be called repeatedly. Returns -EINVAL if attempting to
  * reinitialize with a different number of slots.
  */