doxygen: enable AUTOBRIEF, drop \brief

Especially for short descriptions, it is annoying to have to type \brief for
every single API doc.

Drop all \brief and enable the AUTOBRIEF feature of doxygen, which always takes
the first sentence of an API doc as the brief description.

Change-Id: I11a8a821b065a128108641a2a63fb5a2b1916e87
diff --git a/src/timer.c b/src/timer.c
index 72176b8..e18195a 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -26,7 +26,7 @@
 
 /*! \addtogroup timer
  *  @{
- *  \brief Osmocom timer abstraction; modelled after linux kernel timers
+ *  Osmocom timer abstraction; modelled after linux kernel timers
  */
 
 /*! \file timer.c */
@@ -65,7 +65,7 @@
         rb_insert_color(&timer->node, &timer_root);
 }
 
-/*! \brief set up timer callback and data
+/*! set up timer callback and data
  *  \param[in] timer the timer that should be added
  *  \param[in] callback function to be called when timer expires
  *  \param[in] pointer to data that passed to the callback function
@@ -77,7 +77,7 @@
 	timer->data	= data;
 }
 
-/*! \brief add a new timer to the timer management
+/*! add a new timer to the timer management
  *  \param[in] timer the timer that should be added
  */
 void osmo_timer_add(struct osmo_timer_list *timer)
@@ -88,7 +88,7 @@
 	__add_timer(timer);
 }
 
-/*! \brief schedule a timer at a given future relative time
+/*! schedule a timer at a given future relative time
  *  \param[in] timer the to-be-added timer
  *  \param[in] seconds number of seconds from now
  *  \param[in] microseconds number of microseconds from now
@@ -110,7 +110,7 @@
 	osmo_timer_add(timer);
 }
 
-/*! \brief delete a timer from timer management
+/*! delete a timer from timer management
  *  \param[in] timer the to-be-deleted timer
  *
  * This function can be used to delete a previously added/scheduled
@@ -127,7 +127,7 @@
 	}
 }
 
-/*! \brief check if given timer is still pending
+/*! check if given timer is still pending
  *  \param[in] timer the to-be-checked timer
  *  \return 1 if pending, 0 otherwise
  *
@@ -139,7 +139,7 @@
 	return timer->active;
 }
 
-/*! \brief compute the remaining time of a timer
+/*! compute the remaining time of a timer
  *  \param[in] timer the to-be-checked timer
  *  \param[in] now the current time (NULL if not known)
  *  \param[out] remaining remaining time until timer fires
@@ -167,7 +167,7 @@
 	return 0;
 }
 
-/*! \brief Determine time between now and the nearest timer
+/*! Determine time between now and the nearest timer
  *  \returns pointer to timeval of nearest timer, NULL if there is none
  *
  * if we have a nearest time return the delta between the current
@@ -198,7 +198,7 @@
 	}
 }
 
-/*! \brief Find the nearest time and update nearest_p */
+/*! Find the nearest time and update nearest_p */
 void osmo_timers_prepare(void)
 {
 	struct rb_node *node;
@@ -216,7 +216,7 @@
 	}
 }
 
-/*! \brief fire all timers... and remove them */
+/*! fire all timers... and remove them */
 int osmo_timers_update(void)
 {
 	struct timeval current_time;
@@ -261,7 +261,7 @@
 	return work;
 }
 
-/*! \brief Check how many timers we have in the system
+/*! Check how many timers we have in the system
  *  \returns number of \ref osmo_timer_list registered */
 int osmo_timers_check(void)
 {