gprs_gmm: Avoid spaces in fsm events and enum strings

FSM doesn't expect receiving event names containing spaces (log lines
generated are confusing).

Similar for enums, it's better using code names to match easily and make
log lines more clear.

Change-Id: I16ede8bf8352b09bc772fd7b43fad2c2274b3ec1
diff --git a/src/gprs/gprs_gmm_attach.c b/src/gprs/gprs_gmm_attach.c
index 1ab11f7..2217b0a 100644
--- a/src/gprs/gprs_gmm_attach.c
+++ b/src/gprs/gprs_gmm_attach.c
@@ -316,17 +316,17 @@
 };
 
 const struct value_string gmm_attach_req_fsm_event_names[] = {
-	{ E_ATTACH_REQ_RECV,		"Received an attach request" },
-	{ E_IDEN_RESP_RECV,		"Identity Request received" },
-	{ E_AUTH_RESP_RECV_SUCCESS,	"Authentication Response received" },
-	{ E_AUTH_RESP_RECV_RESYNC,	"Authentication Failure with resync received" },
-	{ E_ATTACH_ACCEPTED,		"Attach accepted" },
-	{ E_ATTACH_ACCEPT_SENT,		"Attach accept sent" },
-	{ E_ATTACH_COMPLETE_RECV, 	"Attach complete received." },
-	{ E_IU_SECURITY_CMD_COMPLETE,   "IU Security Command Complete received." },
-	{ E_REJECT,			"Reject the MS"},
-	{ E_VLR_ANSWERED,		"VLR answered"},
-	{ 0,				NULL }
+	OSMO_VALUE_STRING(E_ATTACH_REQ_RECV),
+	OSMO_VALUE_STRING(E_IDEN_RESP_RECV),
+	OSMO_VALUE_STRING(E_AUTH_RESP_RECV_SUCCESS),
+	OSMO_VALUE_STRING(E_AUTH_RESP_RECV_RESYNC),
+	OSMO_VALUE_STRING(E_ATTACH_ACCEPTED),
+	OSMO_VALUE_STRING(E_ATTACH_ACCEPT_SENT),
+	OSMO_VALUE_STRING(E_ATTACH_COMPLETE_RECV),
+	OSMO_VALUE_STRING(E_IU_SECURITY_CMD_COMPLETE),
+	OSMO_VALUE_STRING(E_REJECT),
+	OSMO_VALUE_STRING(E_VLR_ANSWERED),
+	{ 0, NULL }
 };
 
 void gmm_attach_allstate_action(struct osmo_fsm_inst *fi, uint32_t event, void *data) {