tty: serial: fsl_lpuart: add imx8qxp support

The lpuart of imx8ulp is basically the same as imx7ulp, but it
has new feature support based on imx7ulp, like it can assert a
DMA request on EOP(end-of-packet). imx8ulp lpuart use two clocks,
one is ipg bus clock that is used to access registers, the other
is baud clock that is used to transmit-receive data.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Link: https://lore.kernel.org/r/20190704134007.2316-1-fugang.duan@nxp.com


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