net: stmmac: dwmac-loongson: Drop duplicated hash-based filter size init

The plat_stmmacenet_data::multicast_filter_bins field is twice
initialized in the loongson_default_data() method. Drop the redundant
initialization, but for the readability sake keep the filters init
statements defined in the same place of the method.

Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn>
Signed-off-by: Yinggang Gu <guyinggang@loongson.cn>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>