MHZ_TO_KHZ, and KHZ_TO_MHZ are useful to drivers and
elsewhere so export these in the common ieee80211 header.
Move the power helpers also because we might as well.
Signed-off-by: NThomas Pedersen <thomas@adapt-ip.com>
Link: https://lore.kernel.org/r/20200402011810.22947-2-thomas@adapt-ip.comSigned-off-by: NJohannes Berg <johannes.berg@intel.com>