iwlwifi: unify SW rf-kill flow

This patch unifies SW rf-kill flow between 4965 and 5000. It enables SW
RF-kill for 5000. This patch also solves a bug in iwl4965_mac_config:
bad mutex locking balance.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>