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>

arch/Kconfig

@@ -14,6 +14,7 @@ config ARC
 	select HAVE_PRIVATE_LIBGCC
 	select HAVE_GENERIC_BOARD
 	select SYS_GENERIC_BOARD
+	select SUPPORT_OF_CONTROL
 
 config ARM
 	bool "ARM architecture"