net: dsa: qca8k: move qca8xxx hol fixup to separate function

Move qca8xxx hol fixup to separate function to tidy things up and to
permit using a more efficent loop in future patch.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20230730074113.21889-4-ansuelsmth@gmail.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>