ftrace: Add update_ftrace_direct_add function

ftrace: Add update_ftrace_direct_add function

Adding update_ftrace_direct_add function that adds all entries
(ip -> addr) provided in hash argument to direct ftrace ops
and updates its attachments.

The difference to current register_ftrace_direct is
 - hash argument that allows to register multiple ip -> direct
   entries at once
 - we can call update_ftrace_direct_add multiple times on the
   same ftrace_ops object, becase after first registration with
   register_ftrace_function_nolock, it uses ftrace_update_ops to
   update the ftrace_ops object

This change will allow us to have simple ftrace_ops for all bpf
direct interface users in following changes.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/bpf/20251230145010.103439-5-jolsa@kernel.org