smpp: fix password[] length in struct esme

Change-Id: I07e7193460580a3c972a24700e75c925d1e50411
diff --git a/include/osmocom/smpp/smpp.h b/include/osmocom/smpp/smpp.h
index d48cd79..0d34345 100644
--- a/include/osmocom/smpp/smpp.h
+++ b/include/osmocom/smpp/smpp.h
@@ -23,7 +23,7 @@
 
 	uint8_t smpp_version;
 	char system_id[SMPP_SYS_ID_LEN + 1];
-	char password[SMPP_SYS_ID_LEN + 1];
+	char password[SMPP_PASSWD_LEN + 1];
 };
 
 #define LOGPESME(ESME, LEVEL, FMT, ARGS...)            \