ARM: shmobile: kzm9g: Support Real Time Clock

KZM-A9-GT board has RTC device r2025d at I2C channel 0
with slave address 0x64.

This patch enables reading and writing hardware real time clock on
KZM-A9-GT board. Interrupt is not yet supported.

How to test this patch using user space command.

Read RTC
 # hwclock -r

Copy system clock to RTC
 # hwclock -w

Shutdown and power off the board, and wait a while, then power on again.
Check RTC still keeps correct date.

Signed-off-by: Tetsuyuki Kobayashi <koba@kmckk.co.jp>
Tested-by: Simon Horman <horms@verge.net.au>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

arch/arm/configs/kzm9g_defconfig

@@ -108,6 +108,7 @@ CONFIG_MMC_SH_MMCIF=y
 CONFIG_NEW_LEDS=y
 CONFIG_LEDS_CLASS=y
 CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_RS5C372=y
 CONFIG_DMADEVICES=y
 CONFIG_SH_DMAE=y
 CONFIG_ASYNC_TX_DMA=y

arch/arm/mach-shmobile/board-kzm9g.c

@@ -338,6 +338,9 @@ static struct pcf857x_platform_data pcf8575_pdata = {
 static struct i2c_board_info i2c0_devices[] = {
 	{
 		I2C_BOARD_INFO("ak4648", 0x12),
+	},
+	{
+		I2C_BOARD_INFO("r2025sd", 0x32),
 	}
 };