of_mdio: Don't phy_scan_fixups() twice

The "phy_device_register()" call 5 lines down already calls
phy_scan_fixups(), there's no need to do it a second time.

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>