[PORT FROM R2] mid_pmu: remove sram save/restore from pmu

[PORT FROM R2] mid_pmu: remove sram save/restore from pmu

BZ: 24157

Removing sram save/restore from PMU driver code, since
now it is taken care in SCU itself.

Change-Id: Ic98d68506bfaf39ed478de5d2511a4e1cbe30004
Orig-Change-Id: Ib144c060bf9a321e4329083cc85f9279357ea59c
Signed-off-by: Illyas Mansoor <illyas.mansoor@intel.com>
Reviewed-on: http://android.intel.com:8080/39428
Reviewed-by: Martin, LoicX <loicx.martin@intel.com>
Reviewed-by: Monroy, German <german.monroy@intel.com>
Tested-by: Martin, LoicX <loicx.martin@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>