iwlwifi: contextify command sending

iwlwifi: contextify command sending

Some commands will have different command IDs
for different contexts, so we need to store
those IDs in the context structure and use
them instead of hardcoding the commands.

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