drm/amdgpu: Add support for filling a buffer with 64 bit value

That function will be used later to support setting a page table
block with 64 bit value.

Signed-off-by: Yong Zhao <Yong.Zhao@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2 files changed