amdgfx/gfx: don't use static objects for ce/de meta. (v2)

This isn't safe if we have multiple GPUs plugged in, since
there is only one copy of this struct in the bss, just allocate
on stack, it's 40/108 bytes which should be safe.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>