net: switchdev: Drop EXPERIMENTAL from description

Switchdev has been around for quite a while now, putting "EXPERIMENTAL"
in the description is no longer accurate, drop it.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>