cfg80211: Fix parsed country IE info for 5 GHz

The country IE number of channels on 5 GHz specifies the number
of 5 GHz channels, not the number of sequential channel numbers.
For example, if in a country IEs if the first channel given is 36
and the number of channels passed is 4 then the individual channel
numbers defined for the 5 GHz PHY by these parameters

are: 36, 40, 44, 48
not: 36, 37, 38, 39

See: http://tinyurl.com/11d-clarification



Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>