libmsc/ran_msg_a.c: refactor ran_a_decode_lcls_notification()

We basically need to make sure that one of two possible IEs
is not NULL, while another is NULL (eXclusive OR). This can
be done using at least two conditional branches.

Change-Id: Ie0f9b5c1bbbfb744e0615da07d76037d91b0abc8
Fixes: CID#198444 Logically dead code
diff --git a/src/libmsc/ran_msg_a.c b/src/libmsc/ran_msg_a.c
index da32a84..21be896 100644
--- a/src/libmsc/ran_msg_a.c
+++ b/src/libmsc/ran_msg_a.c
@@ -375,13 +375,7 @@
 	struct ran_msg ran_dec_msg;
 
 	/* Either §3.2.2.119 LCLS-BSS-Status or §3.2.2.120 LCLS-Break-Request shall be present */
-	if ((!ie_lcls_bss_status && !ie_lcls_break_req)
-	    || (ie_lcls_bss_status && ie_lcls_break_req)) {
-		LOG_RAN_A_DEC(ran_dec, LOGL_ERROR, "Ignoring broken LCLS Notification message\n");
-		return -EINVAL;
-	}
-
-	if (ie_lcls_bss_status) {
+	if (ie_lcls_bss_status && !ie_lcls_break_req) {
 		ran_dec_msg = (struct ran_msg){
 			.msg_type = RAN_MSG_LCLS_STATUS,
 			.msg_name = "BSSMAP LCLS Notification (LCLS Status)",
@@ -391,9 +385,7 @@
 			},
 		};
 		return ran_decoded(ran_dec, &ran_dec_msg);
-	}
-
-	if (ie_lcls_break_req) {
+	} else if (ie_lcls_break_req && !ie_lcls_bss_status) {
 		ran_dec_msg = (struct ran_msg){
 			.msg_type = RAN_MSG_LCLS_BREAK_REQ,
 			.msg_name = "BSSMAP LCLS Notification (LCLS Break Req)",
@@ -404,6 +396,7 @@
 		return ran_decoded(ran_dec, &ran_dec_msg);
 	}
 
+	LOG_RAN_A_DEC(ran_dec, LOGL_ERROR, "Ignoring broken LCLS Notification message\n");
 	return -EINVAL;
 }