iwlwifi: mvm: re-aggregate shared queue after unsharing

When a shared queue becomes unshared, aggregations should be
re-enabled if they've existed before. Make sure that they do
this, if required.

Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>