[ril] Don't limit MTU for non-MMS contexts

Larger MTU means better throughput, and the original problem for which
this workaround was implemented was specific to MMS. There's no reason
to limit MTU for other data connections.

ofono/drivers/ril/ril_gprs_context.c

@@ -29,7 +29,7 @@
 
 #define CTX_ID_NONE ((unsigned int)(-1))
 
-#define MAX_MTU 1280
+#define MAX_MMS_MTU 1280
 
 struct ril_gprs_context_call {
 	struct ril_data_request *req;
@@ -108,8 +108,15 @@ static void ril_gprs_context_set_active_call(struct ril_gprs_context *gcd,
 	if (call) {
 		ril_data_call_free(gcd->active_call);
 		gcd->active_call = ril_data_call_dup(call);
-		if (!gcd->mtu_watch) {
-			gcd->mtu_watch = mtu_watch_new(MAX_MTU);
+		if (ofono_gprs_context_get_type(gcd->gc) ==
+					OFONO_GPRS_CONTEXT_TYPE_MMS) {
+			/*
+			 * Some MMS providers have a problem with MTU
+			 * greater than 1280. Let's be safe.
+			 */
+			if (!gcd->mtu_watch) {
+				gcd->mtu_watch = mtu_watch_new(MAX_MMS_MTU);
+			}
 		}
 		mtu_watch_set_ifname(gcd->mtu_watch, call->ifname);
 		ril_data_call_grab(gcd->data, call->cid, gcd);