drm/amdgpu: handle PCIe root ports with addressing limitations

amdgpu uses a need_dma32 flag to indicate to the drm core that some
allocations need to be done using GFP_DMA32, but it only checks the
device addressing capabilities to make that decision.  Unfortunately
PCIe root ports that have limited addressing exist as well.  Use the
dma_addressing_limited instead to also take those into account.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>