Both branches of the regulatory check in ath_attach() set up a
custom regulatory domain and apply radar and world flags, so extract
those into a single path.

While at it, fix a couple of spelling errors and an unnecessary extra
pointer traversal.
Signed-off-by: NBob Copeland <me@bobcopeland.com>
Acked-by: NLuis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>