tracing: Fix desc in error path for the trace remote test module

tracing: Fix desc in error path for the trace remote test module

During initialisation in remote_test_load(), if one of the
simple_ring_buffer fails to initialise, the error path attempts to
rollback initialised buffers. However, the rollback incorrectly uses the
global pointer to the trace descriptor, which is only set upon
successful load completion. Fix the error path by using the local
pointer to the descriptor.

Link: https://patch.msgid.link/20260515201616.337469-1-vdonnefort@google.com
Fixes: ea908a2b79c8 ("tracing: Add a trace remote module for testing")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
base-commit: 5d6919055dec134de3c40167a490f33c74c12581
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>