r8152: Check for unplug in rtl_phy_patch_request()

If the adapter is unplugged while we're looping in
rtl_phy_patch_request() we could end up looping for 10 seconds (2 ms *
5000 loops). Add code similar to what's done in other places in the
driver to check for unplug and bail.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>