arm64: dts: imx8mm-verdin: use level interrupt for mcp251xfd

Switch to level interrupt for mcp251xfd. This will make sure no
interrupts are lost.

Signed-off-by: Andrejs Cainikovs <andrejs.cainikovs@toradex.com>
Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Fixes: 6a57f224

 ("arm64: dts: freescale: add initial support for verdin imx8m mini")
Signed-off-by: Shawn Guo <shawnguo@kernel.org>