iwlwifi: api: remove datamember from struct

We don't use this, but we embed this struct elsewhere and
having structs with flexible arrays embedded isn't quite
right, with sparse (for example) complaining. Remove the
data[] member in this case.

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.20210819183728.72ca1232b27c.I6ec766691b89670e1683f9fc0fbd12648309a574@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>