lapd: Upate the assert to OSMO_ASSERT and describe what we would like to have

Update the OSMO_ASSERT to what it should be like but can't due a
known issue in the LAPDm code.
diff --git a/tests/lapd/lapd_test.c b/tests/lapd/lapd_test.c
index 4d91fee..1f986bc 100644
--- a/tests/lapd/lapd_test.c
+++ b/tests/lapd/lapd_test.c
@@ -243,8 +243,8 @@
 		/* Verify the added RSL_IE_L3_INFO but we have a bug here */
 		OSMO_ASSERT(msg->data[6] == RSL_IE_L3_INFO);
 		#warning "RSL_IE_L3_INFO 16 bit length is wrong"
-		/* ASSERT(msg->data[7] == 0x0 && msg->data[8] == 0x0c); */
-		/* this should be 0x0 and 0x0... but we have a bug */
+		/* This should be okay but it is actually 0x0, 0x9c on ia-32 */
+		/* OSMO_ASSERT(msg->data[7] == 0x0 && msg->data[8] == 0x0); */
 	} else if (state->ms_read == 1) {
 		printf("MS: Verifying incoming MM message: %d\n", msgb_l3len(msg));
 		OSMO_ASSERT(msgb_l3len(msg) == 3);