tty: serial: imx: Add return value check for platform_get_irq()

RX irq is required, so add return value check for platform_get_irq().

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1589180996-618-1-git-send-email-Anson.Huang@nxp.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>