rtc: ds1374: remove unused variable

Fix warning:

drivers/rtc/rtc-ds1374.c: In function ‘ds1374_wdt_disable’:
drivers/rtc/rtc-ds1374.c:442:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]

Link: https://lore.kernel.org/r/20191122102212.400158-3-alexandre.belloni@bootlin.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>