dma-buf: Change st-dma-resv.c to use kunit

dma-buf: Change st-dma-resv.c to use kunit

Modernize the open coded test framework by using kunit.

The kunit tool can be used to build a kernel and run it in a VM with:

$ tools/testing/kunit/kunit.py run --build_dir build_kunit_x86_64 --arch x86_64 --kunitconfig ./drivers/dma-buf/.kunitconfig

Along with the other ways to run kunits.

To make the kunit tool work like this the DMABUF_KUNIT_TEST kconfig must
select DMA_SHARED_BUFFER to get it turned on without building a driver
using it.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/1-v1-0a349a394eff+14110-dmabuf_kunit_jgg@nvidia.com