ARM: dts: BCM53573: Fix Tenda AC9 switch CPU port

Primary Ethernet interface is connected to the port 8 (not 5).

Fixes: 64612828 ("ARM: dts: BCM53573: Add Tenda AC9 switch ports")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20230723195416.7831-1-zajec5@gmail.com


Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>