mac80211: Allow switching of the ath10k regulatory domain (#1001)

ath10k has to switch the regulatory domain when switching the default
country when ATH_USER_REGD is enabled. This is for example important when
switching from country US (FCC) to DE (ETSI). The ath implementation will
use ath_reg_dyn_country_user_allow to check if this is allowed.

Unfortunately, this function always seems to return false to
ath_reg_notifier_apply even when ATH_USER_REGD is enabled. But it must
actually always accept the requests from the user (when ATH_USER_REGD is
enabled) to correctly set the conformance test limits in the ath10k binary
blob.

Not doing it will sometimes allow too high transmit powers on edge channels
for correctly calibrated devices outside their default regulatory domain.

Signed-off-by: Sven Eckelmann <sven.eckelmann@open-mesh.com>