ring-buffer: Return 0 on success from ring_buffer_resize()

We don't need to check the new buffer size, and the return value
had confused resize_buffer_duplicate_size().
...
	ret = ring_buffer_resize(trace_buf->buffer,
		per_cpu_ptr(size_buf->data,cpu_id)->entries, cpu_id);
	if (ret == 0)
		per_cpu_ptr(trace_buf->data, cpu_id)->entries =
			per_cpu_ptr(size_buf->data, cpu_id)->entries;
...

Link: https://lkml.kernel.org/r/20201019142242.11560-1-hqjagain@gmail.com

Cc: stable@vger.kernel.org
Fixes: d60da506

 ("tracing: Add a resize function to make one buffer equivalent to another buffer")
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>