iwlwifi: avoid commit rxon during scan in iwl_set_no_assoc

Currently we are canceling scan when changing BSSID. Behave the same
when changing association and beacon enablement, to avoid committing
rxon during scan in iwl_set_no_assoc().

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>