octeontx2-af: convert dev_dbg to tracepoint in mbox

Use tracepoint instead of dev_dbg since the entire
mailbox code uses tracepoints for debugging.

Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Link: https://patch.msgid.link/1747136408-30685-2-git-send-email-sbhatta@marvell.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>