ath9k_hw: split initvals.h by hardware family

The initvals.h file is over 7000 lines now, so instead of adding
AR9003 initvals to it instead lets split the current initvals.h by
hardware family: AR5008, AR9001, AR9002

The AR9003 family will have its own initval file later.

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