sgsn: Make ra_id_equals available as gprs_ra_id_equals

The function is moved to gprs_utils.c, renamed, and made non-static
to be usable in other modules, too.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/gprs/gprs_utils.c b/openbsc/src/gprs/gprs_utils.c
index ad479db..895a033 100644
--- a/openbsc/src/gprs/gprs_utils.c
+++ b/openbsc/src/gprs/gprs_utils.c
@@ -26,6 +26,7 @@
 #include <osmocom/gprs/gprs_ns.h>
 
 #include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/gsm48.h>
 
 #include <string.h>
 
@@ -399,3 +400,9 @@
 	return -1;
 }
 
+int gprs_ra_id_equals(const struct gprs_ra_id *id1,
+			const struct gprs_ra_id *id2)
+{
+	return (id1->mcc == id2->mcc && id1->mnc == id2->mnc &&
+		id1->lac == id2->lac && id1->rac == id2->rac);
+}