watchdog: orion_wdt: support pretimeout on Armada-XP

Commit e07a4c79

 ("watchdog: orion_wdt: use timer1 as a pretimeout")
added support for a pretimeout on Armada-38x variants. Because the
Armada-XP variants use armada370_start/armada370_stop (due to missing an
explicit RSTOUT mask bit for the watchdog). Add the required pretimeout
support to armada370_start/armada370_stop for Armada-XP.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220211003257.2037332-3-chris.packham@alliedtelesis.co.nz
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>