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/gsm/sysinfo.c b/src/gsm/sysinfo.c
index b5ebd57..201acfc 100644
--- a/src/gsm/sysinfo.c
+++ b/src/gsm/sysinfo.c
@@ -125,7 +125,7 @@
 	{ 0, NULL }
 };
 
-/*! \brief Add pair of arfcn and measurement bandwith value to earfcn struct
+/*! Add pair of arfcn and measurement bandwith value to earfcn struct
  *  \param[in,out] e earfcn struct
  *  \param[in] arfcn EARFCN value, 16 bits
  *  \param[in] meas_bw measurement bandwith value
@@ -144,7 +144,7 @@
 	return -ENOMEM;
 }
 
-/*! \brief Return number of bits necessary to represent earfcn struct as
+/*! Return number of bits necessary to represent earfcn struct as
  *  Repeated E-UTRAN Neighbour Cells IE from 3GPP TS 44.018 Table 10.5.2.33b.1
  *  \param[in,out] e earfcn struct
  *  \returns number of bits
@@ -154,7 +154,7 @@
 	return osmo_earfcn_bit_size_ext(e, 0);
 }
 
-/*! \brief Return number of bits necessary to represent earfcn struct as
+/*! Return number of bits necessary to represent earfcn struct as
  *  Repeated E-UTRAN Neighbour Cells IE from 3GPP TS 44.018 Table 10.5.2.33b.1
  *  \param[in,out] e earfcn struct
  *  \param[in] offset into earfcn struct: how many EARFCNs to skip while estimating size
@@ -183,7 +183,7 @@
 	return bits;
 }
 
-/*! \brief Delete arfcn (and corresponding measurement bandwith) from earfcn
+/*! Delete arfcn (and corresponding measurement bandwith) from earfcn
  *  struct
  *  \param[in,out] e earfcn struct
  *  \param[in] arfcn EARFCN value, 16 bits
@@ -202,7 +202,7 @@
 	return -ENOENT;
 }
 
-/*! \brief Initialize earfcn struct
+/*! Initialize earfcn struct
  *  \param[in,out] e earfcn struct
  */
 void osmo_earfcn_init(struct osmo_earfcn_si2q *e)