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/gprs/protocol/gsm_08_18.h b/include/osmocom/gprs/protocol/gsm_08_18.h
index 529e988..8bc9a8e 100644
--- a/include/osmocom/gprs/protocol/gsm_08_18.h
+++ b/include/osmocom/gprs/protocol/gsm_08_18.h
@@ -2,11 +2,11 @@
 
 #include <stdint.h>
 
-/*! \brief Fixed BVCI definitions (Section 5.4.1) */
+/*! Fixed BVCI definitions (Section 5.4.1) */
 #define BVCI_SIGNALLING	0x0000
 #define BVCI_PTM	0x0001
 
-/*! \brief BSSGP PDU types (Section 11.3.26 / Table 11.27) */
+/*! BSSGP PDU types (Section 11.3.26 / Table 11.27) */
 enum bssgp_pdu_type {
 	/* PDUs between RL and BSSGP SAPs */
 	BSSGP_PDUT_DL_UNITDATA		= 0x00,
@@ -52,7 +52,7 @@
 	BSSGP_PDUT_DELETE_BSS_PFC_ACK	= 0x57,
 };
 
-/*! \brief BSSGP User-Data header (Section 10.2.1 and 10.2.2) */
+/*! BSSGP User-Data header (Section 10.2.1 and 10.2.2) */
 struct bssgp_ud_hdr {
 	uint8_t pdu_type;	/*!< BSSGP PDU type */
 	uint32_t tlli;		/*!< Temporary Link-Local Identifier */
@@ -60,13 +60,13 @@
 	uint8_t data[0];	/* optional/conditional IEs as TLVs */
 } __attribute__((packed));
 
-/*! \brief BSSGP normal header */
+/*! BSSGP normal header */
 struct bssgp_normal_hdr {
 	uint8_t pdu_type;	/*!< BSSGP PDU type */
 	uint8_t data[0];	/*!< optional/conditional IEs as TLVs */
 };
 
-/*! \brief BSSGP Information Element Identifiers */
+/*! BSSGP Information Element Identifiers */
 enum bssgp_iei_type {
 	BSSGP_IE_ALIGNMENT		= 0x00,
 	BSSGP_IE_BMAX_DEFAULT_MS	= 0x01,
@@ -116,7 +116,7 @@
 	BSSGP_IE_SERVICE_UTRAN_CCO	= 0x3d,
 };
 
-/*! \brief Cause coding (Section 11.3.8 / Table 11.10) */
+/*! Cause coding (Section 11.3.8 / Table 11.10) */
 enum gprs_bssgp_cause {
 	BSSGP_CAUSE_PROC_OVERLOAD	= 0x00,
 	BSSGP_CAUSE_EQUIP_FAIL		= 0x01,