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/include/osmocom/gsm/kasumi.h b/include/osmocom/gsm/kasumi.h
index 8ecf65f..222aece 100644
--- a/include/osmocom/gsm/kasumi.h
+++ b/include/osmocom/gsm/kasumi.h
@@ -9,7 +9,7 @@
 
 #include <stdint.h>
 
-/*! \brief Single iteration of KASUMI cipher
+/*! Single iteration of KASUMI cipher
  *  \param[in] P Block, 64 bits to be processed in this round
  *  \param[in] KLi1 Expanded subkeys
  *  \param[in] KLi2 Expanded subkeys
@@ -23,7 +23,7 @@
  */
 uint64_t _kasumi(uint64_t P, const uint16_t *KLi1, const uint16_t *KLi2, const uint16_t *KOi1, const uint16_t *KOi2, const uint16_t *KOi3, const uint16_t *KIi1, const uint16_t *KIi2, const uint16_t *KIi3);
 
-/*! \brief Implementation of the KGCORE algorithm (used by A5/3, A5/4, GEA3, GEA4 and ECSD)
+/*! Implementation of the KGCORE algorithm (used by A5/3, A5/4, GEA3, GEA4 and ECSD)
  *  \param[in] CA
  *  \param[in] cb
  *  \param[in] cc
@@ -34,7 +34,7 @@
  */
 void _kasumi_kgcore(uint8_t CA, uint8_t cb, uint32_t cc, uint8_t cd, const uint8_t *ck, uint8_t *co, uint16_t cl);
 
-/*! \brief Expand key into set of subkeys - see TS 135 202 for details
+/*! Expand key into set of subkeys - see TS 135 202 for details
  *  \param[in] key (128 bits) as array of bytes
  *  \param[out] KLi1 Expanded subkeys
  *  \param[out] KLi2 Expanded subkeys