kernel: Backport mv88e6xxx patch to keep pvid at 0 if VLAN-unaware and remove hack

kernel: Backport mv88e6xxx patch to keep pvid at 0 if VLAN-unaware and remove hack

Keeping the pvid at 0 when VLAN-unaware makes it possible to drop the
hack introduced in commit 920eaab1d817 ("kernel: DSA roaming fix for
Marvell mv88e6xxx"). Dropping the hack makes it possible to use VLAN
interfaces with VID 1 on DSA ports without problems with FDB.

Signed-off-by: Marek Behún <kabel@kernel.org>
(cherry picked from commit 9caa6f0aa742253901c72f43eebecd2c8da5f127)
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
[drop kernel patch hack from Linux version 5.15, drop paragraph about
backport patch, which is not necessary as it is included in kernel 5.15]