ion: Fix API changes in dma-buf-ref.c

Commit fe5698e7 ("ion: Merge all ION related changes from msm-4.19 to
msm-lahaina") added the file dma-buf-ref.c but it was using an older
kernel API for the stack trace management. Fix up the API to work
with 5.4.

Change-Id: Ic0dedbad6f0603ace4c8dc92e6789e043e7fdfa9
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>