watchdog: coh901327: make use of timeout-secs provided in devicetree

watchdog_init_timeout() will allways pick timeout_param since it
defaults to a valid timeout.

Following best practice described in
Documentation/watchdog/watchdog-kernel-api.txt to make use of
the parameter logic.

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>