dma-buf: fix kerneldoc for renamed members

Those members where renamed, update the kerneldoc as well.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211021141945.84023-1-christian.koenig@amd.com