BACKPORT: dma-buf: Rename debugfs symbols

Rename the debugfs list and mutex so it's clear they are now usable
without the need for CONFIG_DEBUG_FS. The list will always be populated
to support the creation of a BPF iterator for dmabufs.

Signed-off-by: T.J. Mercier <tjmercier@google.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20250522230429.941193-2-tjmercier@google.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>
(cherry picked from commit 89f9dba3)
[TJ: This branch doesn't have commit bfc7bc53 ("dma-buf: Do not
build debugfs related code when !CONFIG_DEBUG_FS"), so dmabuf list
manipulation is open-coded, and CONFIG_DEBUG_FS doesn't protect the
list/mutex yet on this branch. Replace open-coded lock/list_add/unlock
with __dma_buf_list_add, skipping commit bfc7bc53 since we don't
want the CONFIG_DEBUG_FS behavior anyway.]
[TJ: Use the new variable names in dma_buf_get_each]
Bug: 445279336
Signed-off-by: T.J. Mercier <tjmercier@google.com>
Change-Id: Iee035a1eed45764bb0dab2847579f0234f0752ee