uboot-phytec

serial: lpuart: Prepare the driver for DM conversion

Create internal routines which take lpuart's register base as
a parameter, in preparation for driver model conversion.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>