media: videobuf2: Stop using internal dma-buf lock

media: videobuf2: Stop using internal dma-buf lock

All drivers that use dma-bufs have been moved to the updated locking
specification and now dma-buf reservation is guaranteed to be locked
by importers during the mapping operations. There is no need to take
the internal dma-buf lock anymore. Remove locking from the videobuf2
memory allocators.

Acked-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221017172229.42269-21-dmitry.osipenko@collabora.com