iwlwifi: pcie: add support for qu c-step devices

Add support for C-step devices.  Currently we don't have a nice way of
matching the step and choosing the proper configuration, so we need to
switch the config structs one by one.

Cc: stable@vger.kernel.org
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>