net: ftgmac100: Get link speed and duplex for NC-SI

The ethtool of this driver uses the phy API of ethtool
to get the link information from PHY driver.
Because the NC-SI is forced on 100Mbps and full duplex,
the driver connect a fixed-link phy driver for NC-SI.
The ethtool will get the link information from the
fixed-link phy driver.

Signed-off-by: Jacky Chou <jacky_chou@aspeedtech.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20240827030513.481469-1-jacky_chou@aspeedtech.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>