msm: acpuclock-8960: Port AVS hooks to acpuclock-8960

When AVS support is available, it must be disabled during any
CPU frequency or CPU voltage changes. Add the hooks to do this.
Since AVS isn't supported on all variants of Krait that
acpuclock-krait supports, have a flag indicating if AVS is
enabled and only configure AVS if the tables support an AVS
setting.

Change-Id: Ide542596b51af18dece4c062b38173ce6e1bc2a0
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>