Rework nss_port5/6 to use the new multiple configuration implementation
and correctly fix the clocks for these port under some corner case.

This is particularly relevant for device that have 2.5G or 10G port
connected to port5 or port 6 on ipq8074. As the parent are shared
across multiple port it may be required to select the correct
configuration to accomplish the desired clock. Without this patch such
port doesn't work in some specific ethernet speed as the clock will be
set to the wrong frequency as we just select the first configuration for
the related frequency instead of selecting the best one.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20231220221724.3822-4-ansuelsmth@gmail.comSigned-off-by: Bjorn Andersson <andersson@kernel.org>