net: dsa: microchip: fix DCB apptrust configuration on KSZ88x3

Remove KSZ88x3-specific priority and apptrust configuration logic that was
based on incorrect register access assumptions. Also fix the register
offset for KSZ8_REG_PORT_1_CTRL_0 to align with get_port_addr() logic.

The KSZ88x3 switch family uses a different register layout compared to
KSZ9477-compatible variants. Specifically, port control registers need
offset adjustment through get_port_addr(), and do not match the datasheet
values directly.

Commit a1ea5771 ("net: dsa: microchip: dcb: add special handling for
KSZ88X3 family") introduced quirks based on datasheet offsets, which do
not work with the driver's internal addressing model. As a result, these
quirks addressed the wrong ports and caused unstable behavior.

This patch removes all KSZ88x3-specific DCB quirks and corrects the port
control register offset, effectively restoring working and predictable
apptrust configuration.

Fixes: a1ea5771 ("net: dsa: microchip: dcb: add special handling for KSZ88X3 family")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250321141044.2128973-1-o.rempel@pengutronix.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>