This reverts commit 8eca1fb6.

Felix notes that this broke regulatory, leaving channel 12 open for AP
operation in the US regulatory domain where it isn't permitted.

Link: http://mid.gmane.org/53A6C0FF.9090104@openwrt.orgReported-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>