net: dsa: microchip: hook up ksz_switch_alloc() to chip-specific dsa_switch_ops

Now that each switch driver has its own dsa_switch_ops (currently a copy
of ksz_switch_ops), we no longer need ksz_switch_ops and can remove it.

Get to the driver-specific dsa_switch_ops through the ksz_chip_data
structure.
Reorder the alloc()/get_match_data() calls such as to have that
pointer available.

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/20260505-clean-ksz-driver-v1-7-05d70fa42461@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>