watchdog: pnx4008: readout watchdog state

Readout the enabled state so it is possible to get the pre-userspace
handler working. Also, avoid disabling the watchdog to ensure it continues
working and triggers if there is an issue later in the boot or if userspace
fails to start.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Tested-by: Gregory CLEMENT <gregory.clement@bootlin.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>