iommu: arm-smmu: Restore missing call to arm_smmu_write_context_bank

arm_smmu_write_context_bank must be called during the hibernation
restore sequence to restore all registers.

Additionally, enable clocks/regulators as required during hibernation
restore.

Change-Id: Ib9f5854e780e7867c0bd4f220dfcdbfb387b3144
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>