iommu/arm-smmu-v3: Issue a batch of commands to the same cmdq

iommu/arm-smmu-v3: Issue a batch of commands to the same cmdq

The driver calls in different places the arm_smmu_get_cmdq() helper, and
it's fine to do so since the helper always returns the single SMMU CMDQ.
However, with NVIDIA CMDQV extension or SMMU ECMDQ, there can be multiple
cmdqs in the system to select one from. And either case requires a batch
of commands to be issued to the same cmdq. Thus, a cmdq has to be decided
in the higher-level callers.

Add a cmdq pointer in arm_smmu_cmdq_batch structure, and decide the cmdq
when initializing the batch. Pass its pointer down to the bottom function.
Update __arm_smmu_cmdq_issue_cmd() accordingly for single command issuers.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Link: https://lore.kernel.org/r/2cbf5ddefb6ea611e48d67c642271bd24421eb21.1724970714.git.nicolinc@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>