ARM: BCM53016: Specify switch ports for Meraki MR32

the switch identifies itself as a BCM53012 (rev 5)...
This patch has been tested & verified on OpenWrt's
snapshot with Linux 5.10 (didn't test any older kernels).
The MR32 is able to "talk to the network" as before with
OpenWrt's SWITCHDEV b53 driver.

| b53-srab-switch 18007000.ethernet-switch: found switch: BCM53012, rev 5
| libphy: dsa slave smi: probed
| b53-srab-switch 18007000.ethernet-switch poe (uninitialized):
|	PHY [dsa-0.0:00] driver [Generic PHY] (irq=POLL)
| b53-srab-switch 18007000.ethernet-switch: Using legacy PHYLIB callbacks.
|	Please migrate to PHYLINK!
| DSA: tree 0 setup

Reported-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>