iommu: arm-smmu: Abstract power resources from struct arm_smmu_device

Directly containing clock and regulator structures within struct
arm_smmu_device forces the functions which enable/disable/initialize clocks
and regulators to use struct arm_smmu_device. This prevents code reuse.
Future changes will use a second struct which also needs to control clocks
and regulators.

Change-Id: I978d80d25217b8f4d560f02c68e84d3f2da50b2c
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>