ice: add lp_advertising flow control support

Add support for reporting link partner advertising when
ETHTOOL_GLINKSETTINGS defined. Get pause param reports the Tx/Rx
pause configured, and then ethtool issues ETHTOOL_GSET ioctl and
ice_get_settings_link_up reports the negotiated Tx/Rx pause. Negotiated
pause frame report per IEEE 802.3-2005 table 288-3.

$ ethtool --show-pause ens6f0
Pause parameters for ens6f0:
Autonegotiate:  on
RX:             on
TX:             on
RX negotiated:  on
TX negotiated:  on

$ ethtool ens6f0
Settings for ens6f0:
        Supported ports: [ FIBRE ]
        Supported link modes:   25000baseCR/Full
        Supported pause frame use: Symmetric
        Supports auto-negotiation: Yes
        Supported FEC modes: None BaseR RS
        Advertised link modes:  25000baseCR/Full
        Advertised pause frame use: Symmetric Receive-only
        Advertised auto-negotiation: Yes
        Advertised FEC modes: None BaseR RS
        Link partner advertised link modes:  Not reported
        Link partner advertised pause frame use: Symmetric
        Link partner advertised auto-negotiation: Yes
        Link partner advertised FEC modes: Not reported
        Speed: 25000Mb/s
        Duplex: Full
        Port: Direct Attach Copper
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: g
        Wake-on: g
        Current message level: 0x00000007 (7)
                               drv probe link
        Link detected: yes

When ETHTOOL_GLINKSETTINGS is not defined, get pause param reports the
negotiated Tx/Rx pause.

Signed-off-by: Paul Greenwalt <paul.greenwalt@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>