chan_alloc: remove references to lchan_alloc()

The function lchan_alloc() does not exist anymore, however there is
still a prototype definition in chan_alloc.h and a comment in
abis_rsl.c. Lets remove those.

Change-Id: I36227ea306d28587ac70acbe596c7756b23d88c7

include/osmocom/bsc/chan_alloc.h

@@ -24,9 +24,6 @@
 
 struct gsm_subscriber_connection;
 
-/* Allocate a logical channel (SDCCH, TCH, ...) */
-struct gsm_lchan *lchan_alloc(struct gsm_bts *bts, enum gsm_chan_t type, int allow_bigger);
-
 /* Free a logical channel (SDCCH, TCH, ...) */
 void lchan_free(struct gsm_lchan *lchan);
 

src/osmo-bsc/abis_rsl.c

@@ -1378,8 +1378,6 @@ static int rsl_rx_chan_rqd(struct msgb *msg)
 	 * - If SDCCH is not available, try whatever MS requested, if not SDCCH.
 	 * - If there is still no channel available, reject channel request.
 	 *
-	 * lchan_alloc() possibly tries to allocate larger lchans.
-	 *
 	 * Note: If the MS requests not TCH/H, we don't know if the phone
 	 *       supports TCH/H, so we must assign TCH/F or SDCCH.
 	 */