iommu/arm-smmu: fix pud/pmd entry fill sequence

The ARM SMMU driver's population of puds and pmds is broken, since we
iterate over the next level of table repeatedly setting the current
level descriptor to point at the pmd being initialised. This is clearly
wrong when dealing with multiple pmds/puds.

This patch fixes the problem by moving the pud/pmd population out of the
loop and instead performing it when we allocate the next level (like we
correctly do for ptes already). The starting address for the next level
is then calculated prior to entering the loop.

Cc: <stable@vger.kernel.org>
Signed-off-by: Yifan Zhang <zhangyf@marvell.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>