Fix enabling of UMTS UEA encryption

The existing code allowed the user to configure UMTS encryption in the
vty, but we never actually passed this information down to RANAP.  As a
result, the RAN had no chance of ever enabling encryption on the air
interface.

Change-Id: Ieaaa6b23b7337b7edb902fad8031e195e0c5e9d2
Related: OS#4144
diff --git a/include/osmocom/msc/ran_msg.h b/include/osmocom/msc/ran_msg.h
index fd2439f..816ef1f 100644
--- a/include/osmocom/msc/ran_msg.h
+++ b/include/osmocom/msc/ran_msg.h
@@ -102,6 +102,9 @@
 		/* out-argument to return the key to the caller, pass NULL if not needed. */
 		struct geran_encr *chosen_key;
 	} geran;
+	struct {
+		bool uea_encryption;
+	} utran;
 };
 
 struct ran_handover_request {