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_16.h b/include/osmocom/gprs/protocol/gsm_08_16.h
index 56ed594..c3dbe69 100644
--- a/include/osmocom/gprs/protocol/gsm_08_16.h
+++ b/include/osmocom/gprs/protocol/gsm_08_16.h
@@ -12,7 +12,7 @@
 
 /*! \file gprs_ns.h */
 
-/*! \brief Common header of GPRS NS */
+/*! Common header of GPRS NS */
 struct gprs_ns_hdr {
 	uint8_t pdu_type;	/*!< NS PDU type */
 	uint8_t data[0];	/*!< variable-length payload */
@@ -20,7 +20,7 @@
 
 extern const struct value_string gprs_ns_pdu_strings[];
 
-/*! \brief NS PDU Type (TS 08.16, Section 10.3.7, Table 14) */
+/*! NS PDU Type (TS 08.16, Section 10.3.7, Table 14) */
 enum ns_pdu_type {
 	NS_PDUT_UNITDATA	= 0x00,
 	NS_PDUT_RESET		= 0x02,
@@ -43,7 +43,7 @@
 	SNS_PDUT_SIZE_ACK	= 0x13,
 };
 
-/*! \brief NS Control IE (TS 08.16, Section 10.3, Table 12) */
+/*! NS Control IE (TS 08.16, Section 10.3, Table 12) */
 enum ns_ctrl_ie {
 	NS_IE_CAUSE		= 0x00,
 	NS_IE_VCI		= 0x01,
@@ -60,7 +60,7 @@
 	NS_IE_IP_ADDR		= 0x0b,
 };
 
-/*! \brief NS Cause (TS 08.16, Section 10.3.2, Table 13) */
+/*! NS Cause (TS 08.16, Section 10.3.2, Table 13) */
 enum ns_cause {
 	NS_CAUSE_TRANSIT_FAIL		= 0x00,
 	NS_CAUSE_OM_INTERVENTION	= 0x01,