drm/amdgpu: Allow more flags to be set on gem create.

The GEM create flag AMDGPU_GEM_CREATE_VRAM_WIPE_ON_RELEASE
specifies that gem memory contains sensitive information and
should be cleared to prevent snooping.

The COHERENT and UNCACHED gem create flags enable memory
features related to sharing memory across devices.

For CRIU we need to re-create KFD BOs through the
GEM_CREATE IOCTL, so allow those KFD specific flags here as well.
This will also aid us in the future and allows to move
the KFD components over using the render node for allocations.

Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>