ethtool: rename reserved1 memeber in ethtool_drvinfo for expansion ROM version

Renamed the reserved1 member of struct ethtool_drvinfo to erom_version to get
expansion/option ROM version of the adapter if present.

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>