ring-buffer: Introduce ring-buffer remotes

ring-buffer: Introduce ring-buffer remotes

Add ring-buffer remotes to support entities outside of the kernel (such
as firmware or a hypervisor) that writes events into a ring-buffer using
the tracefs format

Require a description of the ring-buffer pages (struct
trace_buffer_desc) and callbacks (swap_reader_page and reset) to set up
the ring-buffer on the kernel side.

Expect the remote entity to maintain and update the meta-page.

Link: https://patch.msgid.link/20260309162516.2623589-4-vdonnefort@google.com
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>