dwc_eth_qos: use DWCEQOS_MSG_DEFAULT

Since debug is hardcoded to 3, the defaults in the DWCEQOS_MSG_DEFAULT
macro are never used, which does not seem to be the intended behaviour
here.  Set debug to -1 like other drivers so that DWCEQOS_MSG_DEFAULT is
actually used by default.

Signed-off-by: Rabin Vincent <rabinv@axis.com>
Signed-off-by: Lars Persson <larper@axis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>