tty: serial: fsl_lpuart: remove the dev.coherent_dma_mask zero setting

tty: serial: fsl_lpuart: remove the dev.coherent_dma_mask zero setting

By default, .of_dma_configure() init dev.coherent_dma_mask to BIT(32) that
match the eDMA address range. If re-init dev.coherent_dma_mask to zero, then
streaming dma mapping will go swiotlb dma_map, if swiotlb is not initalized
then it causes mapping failed.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Link: https://lore.kernel.org/r/20190717051930.15514-2-fugang.duan@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>