wifi: ath11k: Use iommu_paging_domain_alloc()

An iommu domain is allocated in ath11k_ahb_fw_resources_init() and is
attached to ab_ahb->fw.dev in the same function.

Use iommu_paging_domain_alloc() to make it explicit.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20240610085555.88197-12-baolu.lu@linux.intel.com


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