wifi: mac80211: simplify reasoning about EHT capa handling

wifi: mac80211: simplify reasoning about EHT capa handling

Given the code in cfg80211, EHT capa cannot be non-NULL when
HE capa is NULL, but it's easier to reason about it if both
are checked and the compiler will likely integrate the check
with the previous one for HE capa anyway.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230301115906.7413d50d23bc.I6fef7484721be9bd5364f64921fc5e9168495f62@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>