iommu: arm-smmu: Fix use after free of pgtbl_ops

During hibernation restore, new pgtbl_ops was allocated
but not assigned to smmu_domian structure. Hence in the
subsequent freeze call uses outdated pointer and cause
a use after free. Fix it by assigning the newly allocated
pgtbl_ops to smmu_domain.

Change-Id: I8200f5a105c1d78239d0aade357007d27cd8b20e
Signed-off-by: Arun KS <arunks@codeaurora.org>