net: ethernet: stmmac: dwmac-socfpga: fix use-after-free on probe errors

Make sure to call stmmac_dvr_remove() before returning on late probe
errors so that memory is freed, clocks are disabled, and the netdev is
deregistered before its resources go away.

Fixes: 3c201b5a

 ("net: stmmac: socfpga: Remove re-registration of
reset controller")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>