wifi: iwlwifi: api: fix a small upper/lower-case typo

The structure name in the docs should be given in all
lower case matching the actual C declaration.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230816104355.c06f98055dbb.Ie9267108c57edcbb913f0d0f349eac85ca39409b@changeid


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