serial-arc: switch to DM

Now when all infrastructure in ARC is ready for it let's switch ARC UART
to driver model.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Simon Glass <sjg@chromium.org>
7 files changed