mrf24j40: Use level-triggered interrupts

The mrf24j40 generates level interrupts. There are rare cases where it
appears that the interrupt line never gets de-asserted between interrupts,
causing interrupts to be lost, and causing a hung device from the driver's
perspective.  Switching the driver to interpret these interrupts as
level-triggered fixes this issue.
Signed-off-by: Alan Ott <alan@signal11.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ieee802154/mrf24j40.c

@@ -678,7 +678,7 @@ static int mrf24j40_probe(struct spi_device *spi)
 	ret = request_threaded_irq(spi->irq,
 				   NULL,
 				   mrf24j40_isr,
-				   IRQF_TRIGGER_FALLING|IRQF_ONESHOT,
+				   IRQF_TRIGGER_LOW|IRQF_ONESHOT,
 				   dev_name(&spi->dev),
 				   devrec);