rtc: ds1685: fix build error with make W=1

rtc: ds1685: fix build error with make W=1

Fix the following parsing errors when building with W=1:
drivers/rtc/rtc-ds1685.c:1053: error: Cannot parse struct or union!
drivers/rtc/rtc-ds1685.c:1062: error: Cannot parse struct or union!
drivers/rtc/rtc-ds1685.c:1363: warning: cannot understand function prototype: 'struct platform_driver ds1685_rtc_driver = '

Cc: Joshua Kinard <kumba@gentoo.org>
Link: https://lore.kernel.org/r/20191122102212.400158-5-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>