iwlwifi: api: clean up some documentation/bits

Clean up some documentation references and some bits in the enums
to make the documentation more useful.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210210142629.941d963ceb88.I72a89c0161d7beab99bc3a90707796c2a63e4197@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>