net: mvneta: Remove unneeded 'weigth' field

The 'weight' field is only used to pass the weigth to napi initialization
function. This commit removes the field, and instead uses a fixed value to
initialize the napi context.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>