dma-buf: Enable signaling on fence for selftests

Here's enabling software signaling on fence for selftest.

Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220914164321.2156-4-Arvind.Yadav@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>

dma-buf: generalize dma_fence unwrap & merging v3

Introduce a dma_fence_unwrap_merge() macro which allows to unwrap fences
which potentially can be containers as well and then merge them back
together into a flat dma_fence_array.

v2: rename the function, add some more comments about how the wrapper is
used, move filtering of signaled fences into the unwrap iterator,
add complex selftest which covers more cases.
v3: fix signaled fence filtering once more

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220518135844.3338-5-christian.koenig@amd.com

dma-buf: cleanup dma_fence_unwrap selftest v2

The selftests, fix the error handling, remove unused functions and stop
leaking memory in failed tests.

v2: fix the memory leak correctly.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220518135844.3338-2-christian.koenig@amd.com

dma-buf: add dma_fence_unwrap v2

Add a general purpose helper to deep dive into dma_fence_chain/dma_fence_array
structures and iterate over all the fences in them.

This is useful when we need to flatten out all fences in those structures.

v2: some selftests cleanup, improved function naming and documentation

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220311110244.1245-1-christian.koenig@amd.com