watchdog: hpwdt: Initialize pretimeout from module parameter.

When the pretimeout is specified as a module parameter, the
value should be reflected in hpwdt_dev.pretimeout.  The default
(on) case is correct.  But, when disabling pretimeout, the value
should be set to zero in hpwdt_dev.

When compiling w/o CONFIG_HPWDT_NMI_DECODING defined, the pretimeout
module parameter is ignored and the value internally will be 0.

Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>