Use 'ROUTING AREA' consistently, not 'ROUTEING AREA'

The spec unfortuantely uses both terms and has no consistent spelling,
but in our logging output we can at least try to be consistent.
diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c
index cb3ff73..115e898 100644
--- a/openbsc/src/gprs/gprs_gmm.c
+++ b/openbsc/src/gprs/gprs_gmm.c
@@ -1348,7 +1348,7 @@
 		break;
 	case GSM48_MT_GMM_RA_UPD_COMPL:
 		/* only in case SGSN offered new P-TMSI */
-		LOGMMCTXP(LOGL_INFO, mmctx, "-> ROUTEING AREA UPDATE COMPLETE\n");
+		LOGMMCTXP(LOGL_INFO, mmctx, "-> ROUTING AREA UPDATE COMPLETE\n");
 		mmctx_timer_stop(mmctx, 3350);
 		mmctx->t3350_mode = GMM_T3350_MODE_NONE;
 		mmctx->p_tmsi_old = 0;