watchdog: Add an info message if the watchdog reset the system

watchdog: Add an info message if the watchdog reset the system

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Investigating why a device has rebooted can be difficult, especially if
there's no output (for example during a kernel crash) on the serial
console. Some watchdog drivers can tell us if the watchdog has caused
the system to reboot. The corresponding WDIOF_CARDRESET flag is
documented as: "Card previously reset the CPU".

Add an info message if the watchdog supports the WDIOF_CARDRESET flag
and if the boot status indicates that the watchdog has previously reset
the system.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>