ice: add port representor ethtool ops and stats

Introduce the following ethtool operations for VF's representor:
	-get_drvinfo
	-get_strings
	-get_ethtool_stats
	-get_sset_count
	-get_link

In all cases, existing operations were used with minor
changes which allow us to detect if ethtool op was called for
representor. Only VF VSI stats will be available for representor.

Implement ndo_get_stats64 for port representor. This will update
VF VSI stats and read them.

Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>