bnxt_en: Enable and disable RX CTAG and RX STAG VLAN acceleration together.

The hardware can only be set to strip or not strip both the VLAN CTAG and
STAG.  It cannot strip one and not strip the other.  Add logic to
bnxt_fix_features() to toggle both feature flags when the user is toggling
one of them.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>