amd-xgbe: Add support for VLAN filtering

This patch adds support for (imperfect) filtering of
VLAN tag ids using a 16-bit filter hash table.  When
VLANs are added, a 4-bit hash is calculated with the
result indicating the bit in the hash table to set.
This table is used by the hardware to drop packets with
a VLAN id that does not hash to a set bit in the table.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>