regulator: spm_regulator: Add snapshot of spm_regulator driver

This is snapshot of the spm_regulator driver as of
msm-4.14 'commit 89909bd394e299cbe ("Merge "clk:
qcom: gcc-sdm429w: Update plls for SDM429W"")'.

Also replace the __invoke_psci_fn_smc wrapper with arm_smccc_smc as
__invoke_psci_fn_smc is no longer available.

Change-Id: Ia6ded6dc21ecff2114ddd20e26706d9196239956
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>