igc: Fix Pause Frame Advertising

Fix Pause Frame Advertising when getting the advertisement via ethtool.
Remove setting the "advertising" bit in link_ksettings during default
case when Tx and Rx are in off state with Auto Negotiate off.

Below is the original output of advertisement link during Tx and Rx off:
Advertised pause frame use: Symmetric Receive-only

Expected output:
Advertised pause frame use: No

Fixes: 8c5ad0da

 ("igc: Add ethtool support")
Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>
Reviewed-by: Malli C <mallikarjuna.chilakala@intel.com>
Acked-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>