net: mana: Add speed support in mana_get_link_ksettings

Allow mana ethtool get_link_ksettings operation to report
the maximum speed supported by the SKU in mbps.

The driver retrieves this information by issuing a
HWC command to the hardware via mana_query_link_cfg(),
which retrieves the SKU's maximum supported speed.

These APIs when invoked on hardware that are older/do
not support these APIs, the speed would be reported as UNKNOWN.

Before:
$ethtool enP30832s1
> Settings for enP30832s1:
        Supported ports: [  ]
        Supported link modes:   Not reported
        Supported pause frame use: No
        Supports auto-negotiation: No
        Supported FEC modes: Not reported
        Advertised link modes:  Not reported
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Advertised FEC modes: Not reported
        Speed: Unknown!
        Duplex: Full
        Auto-negotiation: off
        Port: Other
        PHYAD: 0
        Transceiver: internal
        Link detected: yes

After:
$ethtool enP30832s1
> Settings for enP30832s1:
        Supported ports: [  ]
        Supported link modes:   Not reported
        Supported pause frame use: No
        Supports auto-negotiation: No
        Supported FEC modes: Not reported
        Advertised link modes:  Not reported
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Advertised FEC modes: Not reported
        Speed: 16000Mb/s
        Duplex: Full
        Auto-negotiation: off
        Port: Other
        PHYAD: 0
        Transceiver: internal
        Link detected: yes

Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
Reviewed-by: Saurabh Singh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Link: https://patch.msgid.link/1750144656-2021-4-git-send-email-ernis@linux.microsoft.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>