cfg80211: remove support for adjacent channel compensation

The only driver that used that was iwlwifi and it removed
support for this. Remove the feature here as well.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20200214232336.a530de38e511.I393bc395f6037c8cca6421ed550e3072dc248aed@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>