uhid(4): Don't read-ahead from the USB IN endpoint.

This avoids an issue where IN endpoint data received from the device right
before the file handle is closed, gets lost.

PR:		263995
MFC after:	1 week
Sponsored by:	NVIDIA Networking

sys/dev/usb/input/uhid.c

@@ -218,6 +218,12 @@ uhid_intr_read_callback(struct usb_xfer *xfer, usb_error_t error)
 				actlen = sc->sc_isize;
 			usb_fifo_put_data(sc->sc_fifo.fp[USB_FIFO_RX], pc,
 			    0, actlen, 1);
+
+			/*
+			 * Do not do read-ahead, because this may lead
+			 * to data loss!
+			 */
+			return;
 		} else {
 			/* ignore it */
 			DPRINTF("ignored transfer, %d bytes\n", actlen);