net: dsa: sja1105: Print the reset reason

Sometimes it can be quite opaque even for me why the driver decided to
reset the switch. So instead of adding dump_stack() calls each time for
debugging, just add a reset reason to sja1105_static_config_reload
calls which gets printed to the console.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>