iommu/amd: Use roundup_pow_two() instead of get_order()

iommu/amd: Use roundup_pow_two() instead of get_order()

If x >= PAGE_SIZE then:

  1 << (get_order(x) + PAGE_SHIFT) == roundup_pow_two()

Inline this into the only caller, compute the size of the HW device table
in terms of 4K pages which matches the HW definition.

Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/17-v4-c8663abbb606+3f7-iommu_pages_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>