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

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

[ Upstream commit 4029dfc034febb54f6dd8ea83568accc943bc088 ]

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

Fixes: 380c966c093e ("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>