tty: serial: fsl_lpuart: add IDLE interrupt support for rx_dma on imx7ulp/imx8ulp/imx8qxp

Add IDLE interrupt support for receive dma on imx7ulp/imx8ulp/imx8qxp
platforms to replace the receive dma timer function, because the receive
dma timer has bigger latency than idle interrupt triggering, which may
cause the Bluetooth Firmware download timeout on Android platform(it
has a limited FW download time window).

Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20230710013857.7396-3-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>