iwlwifi: mvm: Prevent setting assoc flag in MAC_CONTEXT_CMD

In the normal flow first MAC_CONTEXT_CMD for particular interface is
never sent while associated. The exception is fw restart flow when
resuming from suspend when WoWLAN is enabled. In this case successive
"add" and "modify" MAC_CONTEXT_CMD commands may be sent with assoc flag
set what cause FW mal functioning. To prevent this never set assoc flag
in MAC_CONTEXT_CMD with action "add".

Cc: stable@vger.kernel.org
Signed-off-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>