iommu/arm-smmu-v3: Rename cdcfg to cd_table

cdcfg is a confusing name, especially given other variables with the cfg
suffix in this driver. cd_table more clearly describes what is being
operated on.

Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Michael Shavit <mshavit@google.com>
Link: https://lore.kernel.org/r/20230915211705.v8.9.I5ee79793b444ddb933e8bc1eb7b77e728d7f8350@changeid


Signed-off-by: Will Deacon <will@kernel.org>