drivers: ethernet: eth_stm32_hal: fix API_V2 multicast

After API_V2 auto-negotiation support was added by #86621
setup_mac_filter() was called before HAL_ETH_Init(), which resulted in
received multicast packets being discarded.

This moves the call to setup_mac_filter() to eth_iface_init(), after
HAL_ETH_Init() for both API_V1 and API_V2.

I've verified the problem and tested the fix on a Nucleo-H563ZI with a
simple application that just starts up and makes an mDNS query (which
depends on working multicast).

Signed-off-by: Kevin ORourke <kevin.orourke@ferroamp.se>