iwlwifi: mvm: fix error path in iwl_mvm_mac_setup_register()

The IWL_MVM_INIT_STATUS_REG_HW_INIT_COMPLETE bit shouldn't be set,
and realistically we should complete all setup before we call the
ieee80211_register_hw() function. Fix this.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>