ibss: use correct "MHz" instead of "MHZ"
ibss: use correct "MHz" instead of "MHZ"

Signed-off-by: Johannes Berg <bff32994ff0f8d048f262a8388145a71b6071bfe@intel.com>

bw-oss/iw,greearb/iw-ct,bw-oss/iw,greearb/iw-ct