ethtool: EEPROM dump no longer works for tg3 and natsemi

ethtool: EEPROM dump no longer works for tg3 and natsemi

In the ethtool user-space application, tg3 and natsemi over-ride the
default implementation of dump_eeprom(). In both tg3_dump_eeprom() and
natsemi_dump_eeprom(), there is a magic number check which is not
present in the default implementation.

Commit cefdf635 ("[ETHTOOL]: Add support for large eeproms") snipped
the code which copied the ethtool_eeprom structure back to
user-space. tg3 and natsemi are over-writing the magic number field
and then checking it in user-space. With the ethtool_eeprom copy
removed, the check is failing.

The fix is simple. Add the ethtool_eeprom copy back.

Signed-off-by: Mandeep Singh Baines <msb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>