net: dsa: mv88e6xxx: extend fid mask

The driver currently manages one FID per port (or bridge group), with a
mask of DSA_MAX_PORTS bits, where 0 means that the FID is in use.

The Marvell 88E6xxx switches support up to 4094 FIDs (from 1 to 0xfff;
FID 0 means that multiple address databases are not being used).

This patch changes the fid_mask for an fid_bitmap of 4096 bits.

>From now on, FIDs 1 to num_ports are reserved for non-bridged ports and
bridge groups (a bridge group gets the FID of its first member). The
remaining bits will be reserved for VLAN entries.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>