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/logging_gsmtap.c b/src/logging_gsmtap.c
index 7358bf6..9e5884b 100644
--- a/src/logging_gsmtap.c
+++ b/src/logging_gsmtap.c
@@ -24,7 +24,7 @@
  */
 
 /*! \file logging_gsmtap.c
- *  \brief libosmocore log output encapsulated in GSMTAP
+ *  libosmocore log output encapsulated in GSMTAP
  *
  *  Encapsulating the log output inside GSMTAP frames allows us to
  *  observer protocol traces (of Um, Abis, A or any other interface in
@@ -102,7 +102,7 @@
 	gsmtap_sendmsg(target->tgt_gsmtap.gsmtap_inst, msg);
 }
 
-/*! \brief Create a new logging target for GSMTAP logging
+/*! Create a new logging target for GSMTAP logging
  *  \param[in] ident string identifier
  *  \returns Log target in case of success, NULL in case of error
  */