iommu/amd: Allocate the page table root using GFP_KERNEL

iommu/amd: Allocate the page table root using GFP_KERNEL

Domain allocation is always done under a sleepable context, the v1 path
and other drivers use GFP_KERNEL already. Fix the v2 path to also use
GFP_KERNEL.

Fixes: 0d571dcbe7c6 ("iommu/amd: Allocate page table using numa locality info")
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/2-v2-831cdc4d00f3+1a315-amd_iopgtbl_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>