gsm_pchan2chan_nr: disable a chan_nr assert in BTS, to not break octphy

In https://gerrit.osmocom.org/589 , msuraev reports an assertion on octphy.
So disable this recently added assertion until we clarify the invocation in
question.

Change-Id: Ia0f7ae5b114e179ab56b98adbae9810e81b4b88f

openbsc/src/libcommon/gsm_data_shared.c

@@ -592,7 +592,17 @@ uint8_t gsm_pchan2chan_nr(enum gsm_phys_chan_config pchan,
 		break;
 	default:
 	case GSM_PCHAN_CCCH:
+#ifdef ROLE_BSC
 		OSMO_ASSERT(lchan_nr == 0);
+#else
+		/*
+		 * FIXME: On octphy and litecell, we hit above assertion (see
+		 * Max's comment at https://gerrit.osmocom.org/589 ); disabled
+		 * for BTS until this is clarified; remove the #ifdef when it
+		 * is fixed.
+		 */
+#warning "fix caller that passes lchan_nr != 0"
+#endif
 		cbits = 0x10;
 		break;
 	}