watchdog: indydog: Simplify indydog_{start,stop}

This patch simplify functions indydog_start() and indydog_stop()
a bit and removes excess intermediate variable.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>