net: mvpp2: do not bypass the mvpp22_port_mii_set function

The mvpp22_port_mii_set() function was added by 26975821, but the
function directly returns without doing anything. This return was used
when debugging and wasn't removed before sending the patch. Fix this.

Fixes: 26975821 ("net: mvpp2: handle misc PPv2.1/PPv2.2 differences")
Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>