msm: cpr-regulator: remove register save and restore for suspend and resume

As CPR hardware register values will be retained during XO shutdown with
VDD_CX minimization, there is no need to save and restore CPR hardware
register values during suspend and resume. Also, there is a race condition
between cpr_resume and cpr_regulator_set_voltage. The
cpr_regulator_set_voltage function might be called after cpr_suspend is
invoked and before cpr_resume is called, this will enable CPR during XO
shutdown.

Hence remove register save and restore operations from cpr_suspend and
cpr_resume functions and add a flag to indicate that CPR has been
suspended.

Change-Id: Ic7c0f639e7e5cedb096d2f2eaaa3e8433ccd44c7
CRs-Fixed: 616385
Signed-off-by: Ke Liu <keliu@codeaurora.org>