Remove the lag forbid/allow functions, change the lag prereq check to
run in the do-bond logic, so every change in the prereq state will
cause LAG to be disabled/enabled accordingly after the next do-bond run.

Add lag update function, so every component which changes the prereq
state and want the LAG to re-calc the conditions can call the update
function.
Signed-off-by: Rabie Loulou <rabiel@mellanox.com>
Signed-off-by: Aviv Heller <avivh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>