iommu/fsl_pamu: merge iommu_alloc_dma_domain into fsl_pamu_domain_alloc

Keep the functionality to allocate the domain together.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Li Yang <leoyang.li@nxp.com>
Link: https://lore.kernel.org/r/20210401155256.298656-5-hch@lst.de


Signed-off-by: Joerg Roedel <jroedel@suse.de>