iwlwifi: fix wrong struct for a000 device

The PCI ID (0x2720, 0x0070) was set with the config struct
iwla000_2ax_cfg_hr instead of iwla000_2ac_cfg_hr_cdb.

Fixes: 175b87c6 ("iwlwifi: add the new a000_2ax series")
Signed-off-by: Oren Givon <oren.givon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>