move gsm_auth_tuple to vlr.h as vlr_auth_tuple

Along goes GSM_KEYSEQ_INVAL as VLR_*.

It's where it logically belongs, and is almost the only reason why vlr.h
includes gsm_data.h. The remaining reason, GSM_EXTENSION_LENGTH, will be moved
by upcoming patch.

Change-Id: I122feae7ee3cbc59e941daef35a954bce29fec76
diff --git a/tests/msc_vlr/msc_vlr_tests.c b/tests/msc_vlr/msc_vlr_tests.c
index 2443e31..29ffdbf 100644
--- a/tests/msc_vlr/msc_vlr_tests.c
+++ b/tests/msc_vlr/msc_vlr_tests.c
@@ -714,7 +714,7 @@
 	return 0;
 }
 
-static int fake_vlr_tx_auth_req(void *msc_conn_ref, struct gsm_auth_tuple *at,
+static int fake_vlr_tx_auth_req(void *msc_conn_ref, struct vlr_auth_tuple *at,
 				bool send_autn)
 {
 	struct ran_conn *conn = msc_conn_ref;