If the current channel is between 2412 and 2472 MHz and if the channel is
changing to 2484 MHz, then the registers 0xa1f4, 0xa1f8 and 0xa1fc need to be
programmed to the "japan_2484" values.  Conversely, if the current channel
is 2484 MHz and if the channel is changing to one between 2412 and 2472 MHz, then
the three registers need to be programmed to the "normal" values.

This is needed for compliance with Japanese regulatory requirements.
Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>