Although there is an existing code comment about flushing the writes,
writes were not actually being flushed.
Actually flush the writes by changing readl_relaxed() to readl().
Fixes: 4ed224aeaf661 ("watchdog: Add Apple SoC watchdog driver")
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Nick Chan <towinchenmi@xxxxxxxxx>