net: phy: c45: add a separate function to read BASE-T1 abilities

commit f2e90c74714487fd33e79e05f3f3621beb0646ed from
https://github.com/nxp-auto-linux/linux



Add a separate function to read the BASE-T1 abilities. Some PHYs do not
indicate the availability of the extended BASE-T1 ability register, so
this function must be called separately.

Issue: ALB-10440

Signed-off-by: Stefan Eichenberger <eichest@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
(cherry picked from commit eba2e4c2)
Signed-off-by: Zhantao Tang <zhantao.tang@windriver.com>