arm: rmobile: silk: Migrate serial driver to drivers model

This adds drivers model support of serial port to Silk board,
and migrate serial port to drivers model.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/board/renesas/silk/silk.c b/board/renesas/silk/silk.c
index dfd9a9d..8fb729a 100644
--- a/board/renesas/silk/silk.c
+++ b/board/renesas/silk/silk.c
@@ -9,6 +9,8 @@
 
 #include <common.h>
 #include <malloc.h>
+#include <dm.h>
+#include <dm/platform_data/serial_sh.h>
 #include <asm/processor.h>
 #include <asm/mach-types.h>
 #include <asm/io.h>
@@ -161,3 +163,15 @@
 	val |= 0x02;
 	i2c_write(CONFIG_SYS_I2C_POWERIC_ADDR, 0x13, 1, &val, 1);
 }
+
+static const struct sh_serial_platdata serial_platdata = {
+	.base = SCIF2_BASE,
+	.type = PORT_SCIF,
+	.clk = 14745600,
+	.clk_mode = EXT_CLK,
+};
+
+U_BOOT_DEVICE(alt_serials) = {
+	.name = "serial_sh",
+	.platdata = &serial_platdata,
+};