cfg80211: remove get/set antenna and tx power warnings

Since set_tx_power and set_antenna are frequently implemented
without the matching get_tx_power/get_antenna, we shouldn't
have added warnings for those. Remove them.

The remaining ones are correct and need to be implemented
symmetrically for correct operation.

Cc: stable@vger.kernel.org
Fixes: de3bb771

 ("cfg80211: add more warnings for inconsistent ops")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>