core/embed: Set VCP write timeout to 0.

core/embed/firmware/mphalport.c

@@ -33,8 +33,9 @@ int mp_hal_stdin_rx_chr(void) {
 
 void mp_hal_stdout_tx_strn(const char *str, size_t len) {
   if (vcp_iface_num >= 0) {
-    int r =
-        usb_vcp_write_blocking(vcp_iface_num, (const uint8_t *)str, len, 500);
+    // The write timeout is set to 0, because otherwise when the VCP receive
+    // buffer on the host gets full, the timeout will block device operation.
+    int r = usb_vcp_write_blocking(vcp_iface_num, (const uint8_t *)str, len, 0);
     (void)r;
   }
 }