tty: serial: fsl_lpuart: add 7-bits format support on imx7ulp/imx8ulp/imx8qxp

imx7ulp/imx8ulp/imx8qxp lpuart IP support 7-bits format and have no
limitation on parity when CS7. Remove this limitation and add 7-bits
format support on imx7ulp/imx8ulp/imx8qxp.

Signed-off-by: Luke Wang <ziniu.wang_1@nxp.com>
Link: https://lore.kernel.org/r/20241008094418.439706-1-ziniu.wang_1@nxp.com


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