net/mlx5e: Refactor on-the-fly configuration changes

This commit extends mlx5e_safe_switch_channels() to support on-the-fly
configuration changes, when the channels are open, but don't need to be
recreated. Such flows exist when a parameter being changed doesn't
affect how the queues are created, or when the queues can be modified
while remaining active.

Before this commit, such flows were handled as special cases on the
caller site. This commit adds this functionality to
mlx5e_safe_switch_channels(), allowing the caller to pass a boolean
indicating whether it's required to recreate the channels or it's
allowed to skip it. The logic of switching channel parameters is now
completely encapsulated into mlx5e_safe_switch_channels().

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>