drm/vmwgfx: remove vmw_wait_dma_fence

Decomposing fence containers don't seem to make any sense here.

So just remove the function entirely and call dma_fence_wait() directly.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220124130328.2376-12-christian.koenig@amd.com