watchdog: add driver for Ricoh RN5T618 watchdog

This adds a driver for the watchdog timer available in Ricoh RN5T618
PMIC. The device supports a programmable expiration time of 1, 8, 32
or 128 seconds.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 44f5d68..f105999 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -48,6 +48,7 @@
 obj-$(CONFIG_DAVINCI_WATCHDOG) += davinci_wdt.o
 obj-$(CONFIG_ORION_WATCHDOG) += orion_wdt.o
 obj-$(CONFIG_SUNXI_WATCHDOG) += sunxi_wdt.o
+obj-$(CONFIG_RN5T618_WATCHDOG) += rn5t618_wdt.o
 obj-$(CONFIG_COH901327_WATCHDOG) += coh901327_wdt.o
 obj-$(CONFIG_STMP3XXX_RTC_WATCHDOG) += stmp3xxx_rtc_wdt.o
 obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o