pdch: cosmetic: use GSM_MI_TYPE_* constants from libosmocore

Change-Id: I1d85c8eded68bc8aa8e90c33b36d335fa775ded2
diff --git a/src/pdch.cpp b/src/pdch.cpp
index 9910974..9b4d89b 100644
--- a/src/pdch.cpp
+++ b/src/pdch.cpp
@@ -209,7 +209,7 @@
 		     osmo_mi_name(pag->identity_lv + 1, pag->identity_lv[0]));
 
 		/* try to add paging */
-		if ((pag->identity_lv[1] & 0x07) == 4) {
+		if ((pag->identity_lv[1] & GSM_MI_TYPE_MASK) == GSM_MI_TYPE_TMSI) {
 			/* TMSI */
 			len = 1 + 1 + 1 + 32 + 2 + 1;
 			if (pag->identity_lv[0] != 5) {