tracing: Fix unload_page for simple_ring_buffer init rollback

The unload_page callback expects the return value of load_page() as its
argument: ret = load_page(va); unload(ret). Fix the rollback code in
simple_ring_buffer_init_mm() where the descriptor's VA is used instead
of the loaded page address.

Link: https://patch.msgid.link/20260512141614.1759430-1-vdonnefort@google.com
Fixes: 6359230 ("tracing: load/unload page callbacks for simple_ring_buffer")
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Author: vdonnefort

kernel/trace/simple_ring_buffer.c

@@ -430,7 +430,7 @@ int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer,
 
 	if (ret) {
 		for (i--; i >= 0; i--)
-			unload_page((void *)desc->page_va[i]);
+			unload_page(bpages[i].page);
 		unload_page(cpu_buffer->meta);
 
 		return ret;