ath9k: Fix regulatory compliance

The maximum permissible values for noise floor in ETSI
and Japan domains have been updated with new EU
regulations for CCA detection. Adjust the values in the
driver accordingly.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>