iwlwifi: nvm: use iwl_nl80211_band_from_channel_idx

Use iwl_nl80211_band_from_channel_idx in iwl_parse_nvm_mcc_info

Signed-off-by: Tova Mussai <tova.mussai@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200417131727.a64a018f244e.Ie75ac5bb0f0f524d26944800138855ef2228339a@changeid