iwlwifi: trust mac80211 channel setting

mac80211 will never set, switch to, or scan on an
invalid channel, so remove the code to validate
the channels against the driver channel list.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --cc drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-mac80211.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-scan.c
Simple merge