Add ethtool EEPROM read/write support using the eeprom_93cx6
library instead of open-coding the functions.

Depends on eeprom_93cx6 driver getting EEPROM write support.
Signed-off-by: NBen Dooks <ben@simtec.co.uk>
Signed-off-by: NSimtec Linux Team <linux@simtec.co.uk>
[sboyd@codeaurora.org: Removed previous eeprom implementation]
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>