libdrm: Fix amdgpu build failure

Use the correct files to build libdrm_amdgpu.

Signed-of-by: Mike Lothian <mike@fireburn.co.uk>
Fixes: d6cb0ee4 ("amdgpu: remove the hash table implementation")
Cc: Christian König <christian.koenig@amd.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>