Commit 46c5176c586c ("net: dsa: b53: support legacy tags") introduced
support for legacy tags, but it turns out that BCM5325 and BCM5365
switches require the original FCS value and length, so they have to be
treated differently.
Fixes: 46c5176c586c ("net: dsa: b53: support legacy tags")
Signed-off-by: Álvaro Fernández Rojas <noltari@xxxxxxxxx>