ath5k: Misc hw_attach fixes

 * Correctly attach RF2425
 * Update SREV values for Radio chips
 * Update hw_attach to use new SPENDING values
 * Write a bit after POST for some chips

Changes-licensed-under: ISC
Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>