dm: serial: use Driver Model for UniPhier serial driver

This commit converts UniPhier on-chip serial driver to driver model.

Since UniPhier SoCs do not have Device Tree support, some board files
should be added under arch/arm/cpu/armv7/uniphier/ph1-*/ directories.
(Device Tree support for UniPhier platform is still under way.)

Now the base address and master clock frequency are passed from
platform data, so CONFIG_SYS_UNIPHIER_SERIAL_BASE* and
CONFIG_SYS_UNIPHIER_UART_CLK should be removed.

Tested on UniPhier PH1-LD4 ref board.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/cpu/armv7/uniphier/ph1-sld8/Makefile b/arch/arm/cpu/armv7/uniphier/ph1-sld8/Makefile
index b385e19..781b511 100644
--- a/arch/arm/cpu/armv7/uniphier/ph1-sld8/Makefile
+++ b/arch/arm/cpu/armv7/uniphier/ph1-sld8/Makefile
@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_DISPLAY_BOARDINFO) += board_info.o
+obj-y += platdevice.o
 obj-y += boot-mode.o
 obj-$(CONFIG_BOARD_POSTCLK_INIT) += board_postclk_init.o bcu_init.o \
 		sbc_init.o sg_init.o pll_init.o clkrst_init.o pinctrl.o