kernel/timer.c: fix kernel-doc function parameter warning

Fix kernel-doc warning, add @timer description:

Warning(kernel/timer.c:335): No description found for parameter 'timer'

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/timer.c

···
 
 /**
  * set_timer_slack - set the allowed slack for a timer
+ * @timer: the timer to be modified
  * @slack_hz: the amount of time (in jiffies) allowed for rounding
  *
  * Set the amount of time, in jiffies, that a certain timer has