The only consumers of the Realtek HSGMII (2.5G SGMII) mode were
the RTL8226/RTL8221B PHYs. These have been converted to dynamic
SGMII/2500base-x mode switching. Drop the leftovers of the mode
implementation.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/20002
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>