iwlwifi: remove shared lock

Some data doesn't need protection, some of the
lock places are simply useless, and some data
can be protected with the mutex instead. Thus
the shared lock can be removed by making those
changes.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>