msm: msm-pm: Remove outer cache functions

Remove outer cache functions to do cache maintenance
operations because all the newer targets having the
integrated cache controller and cache operations are
done by standard cache maintenance functions.

Change-Id: Iaeaf5bc85ea629b89efabb1d3ea8cc9aa97f9790
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>