fix spelling errors detected by lintian

Change-Id: I381618eb55cc513cfa9c2e384c27cead0935c8bf
diff --git a/src/tbf.h b/src/tbf.h
index 0a58862..34e8101 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -43,7 +43,7 @@
  */
 
 #define T_ASS_AGCH_USEC 200000	/* waiting after IMM.ASS confirm */
-#define T_ASS_PACCH_SEC 2	/* timeout for pacch assigment */
+#define T_ASS_PACCH_SEC 2	/* timeout for pacch assignment */
 #define T_REJ_PACCH_USEC 2000	/* timeout for tbf reject for PRR*/
 
 enum gprs_rlcmac_tbf_state {