Add additional error reporting to the generic DSA code, so it's easier
to debug when things go wrong.  This was useful when initially bringing
up 88e6176 on a new board.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>