bridge: vlan: set vlan option attributes while parsing

bridge: vlan: set vlan option attributes while parsing

Set vlan option attributes immediately while parsing to simplify the
checks, avoid having reserved values (e.g. -1 for unset var) and have
more limited scope for the variables. This is also similar to how global
vlan options are set. The attribute setting and checks are moved with
option parsing, no functional changes intended.

Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David Ahern <dsahern@kernel.org>