watchdog: rn5t618_wdt: fix module aliases

Platform device aliases were missing so module autoloading
did not work.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20191213214802.22268-1-andreas@kemnade.info


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>