net: dsa: microchip: bypass dev_ops for change_mtu() operation

net: dsa: microchip: bypass dev_ops for change_mtu() operation

MTU changing is done through a common function that redirects the
treatment to a specific ksz_dev_ops callback. This layer of indirection
isn't needed since we now have a dsa_switch_ops struct for each switch
family.

Remove this indirection layer in MTU changing for KSZ switches, by
directly connecting the ksz_dev_ops :: change_mtu() implementations to
dsa_switch_ops.
Remove the no longer used change_mtu() callback from ksz_dev_ops

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
Link: https://patch.msgid.link/20260512-clean-ksz-2nd-series-v1-3-c00f6ce037fa@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>