net: sparx5: fix wrong config being used when reconfiguring PCS

The wrong port config is being used if the PCS is reconfigured. Fix this
by correctly using the new config instead of the old one.

Fixes: 946e7fd5

 ("net: sparx5: add port module support")
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20240409-link-mode-reconfiguration-fix-v2-1-db6a507f3627@microchip.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>