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/ipa.c b/src/gsm/ipa.c
index 5c37d64..2c7cf58 100644
--- a/src/gsm/ipa.c
+++ b/src/gsm/ipa.c
@@ -43,7 +43,7 @@
 
 /*! \addtogroup ipa
  *  @{
- *  \brief IPA Multiplex utility routines
+ *  IPA Multiplex utility routines
  */
 
 #define IPA_ALLOC_SIZE 1200
@@ -213,7 +213,7 @@
 
 #define IPA_STRING_MAX 64
 
-/*! \brief Generate IPA CCM ID RESP based on list of IEs
+/*! Generate IPA CCM ID RESP based on list of IEs
  *  \param[in] dev Descriptor describing identity data for response
  *  \param[in] ies_req List of IEIs to include in response
  *  \param[in] num_ies_req Number of IEIs in \a ies_req
@@ -296,7 +296,7 @@
 	return msg;
 }
 
-/*! \brief Generate IPA CCM ID RESP based on requets payload
+/*! Generate IPA CCM ID RESP based on requets payload
  *  \param[in] dev Descriptor describing identity data for response
  *  \param[in] data Payload of the IPA CCM ID GET request
  *  \param[in] len Length of \a data in octets