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/configs/ph1_ld4_defconfig b/configs/ph1_ld4_defconfig
index 53f3126..c8404f8 100644
--- a/configs/ph1_ld4_defconfig
+++ b/configs/ph1_ld4_defconfig
@@ -2,7 +2,9 @@
 +S:CONFIG_ARM=y
 +S:CONFIG_ARCH_UNIPHIER=y
 +S:CONFIG_MACH_PH1_LD4=y
+CONFIG_DM=y
 CONFIG_NAND_DENALI=y
 CONFIG_SYS_NAND_DENALI_64BIT=y
 CONFIG_NAND_DENALI_SPARE_AREA_SKIP_BYTES=8
+CONFIG_DM_SERIAL=y
 S:CONFIG_SPL_NAND_DENALI=y