tty: serial: fsl_lpuart: clear LPUART Status Register in lpuart32_shutdown()

tty: serial: fsl_lpuart: clear LPUART Status Register in lpuart32_shutdown()

[ Upstream commit b79b743ac0495842b502daaee5af1dfad545d95e ]

The LPUART Status Register needs to be cleared when closing the uart
port to get a clean environment when reopening the uart.

Fixes: ecdab422d769 ("tty: serial: fsl_lpuart: add 32-bit register interface support")
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20221125101953.18753-4-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>