Do not break from the loop if an invalid fragment is received

It is highly likely that an invalid fragment will be received so
stopping the receiver after that and restarting the call after each
invalid fragment is very user-hostile

src/formats/hevc_recv_normal.cc

@@ -129,7 +129,7 @@ rtp_error_t __hevc_receiver(kvz_rtp::reader *reader)
         if (type == FT_INVALID) {
             LOG_WARN("invalid frame received!");
             (void)kvz_rtp::frame::dealloc_frame(frame);
-            break;
+            continue;
         }
 
         /* TODO: this is ugly */