ath9k_hw: make two initvals consto for the AR9001 family

This makes ar5416Addac_9160 and ar5416Addac_9160 const
I guess we skipped them long ago.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>