[PATCH 1/2] serial: lpuart: fix RXFE filed offset for i.MX9

[Peng Fan (OSS)]

> Subject: [PATCH 1/2] serial: lpuart: fix RXFE filed offset for i.MX9
> 
> Like i.MX8 and i.MXRT, on i.MX9, the Receive RX FIFO Enable (RXFE)
> field in LPUART FIFO register is bit 3, so set FIFO_RXFE to 0x08 on
> i.MX9 too.
> 
> Signed-off-by: Sébastien Szymanski
> <sebastien.szymanski at armadeus.com>

LGTM: Reviewed-by: Peng Fan <peng.fan at nxp.com>