drm/amdgpu: drop the fence argument from amdgpu_vmid_grab

This is always the job anyway.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221014084641.128280-5-christian.koenig@amd.com