ath9k_hw: Move some RF ops to the private callbacks

The PHY split is easier done in a few steps. First move
the RF ops to the private ops and rename them accordingly.
We split PHY stuff up first for the AR5008 and AR9002
families. There are some callbacks that AR9002 share
with the AR5008 familiy so we set those first, if AR9002
has some different callbacks it will override them upon
hardware init.

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