[BNX2]: simplify parameter checks in bnx2_{get,set}_eeprom

Remove the superfluous parameter checking in bnx2_{get,set}_eeprom.
The parameters are already validated in ethtool_{get,set}_eeprom.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>