iommu/arm-smmu-v3: Fix error check in arm_smmu_alloc_cd_tables

iommu/arm-smmu-v3: Fix error check in arm_smmu_alloc_cd_tables

In arm_smmu_alloc_cd_tables(), the error check following the
dma_alloc_coherent() for cd_table->l2.l1tab incorrectly tests
cd_table->l2.l2ptrs.

This means an allocation failure for l1tab goes undetected, causing
the function to return 0 (success) erroneously.

Correct the check to test cd_table->l2.l1tab.

Fixes: e3b1be2e73db ("iommu/arm-smmu-v3: Reorganize struct arm_smmu_ctx_desc_cfg")
Signed-off-by: Daniel Mentz <danielmentz@google.com>
Signed-off-by: Ryan Huang <tzukui@google.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>