rtla: Simplify osnoise tracer option setting code

Each osnoise tracer option (in /sys/kernel/tracing/osnoise) used by RTLA
requires four functions to be defined:

- static osnoise_get_<opt>() - to get the current value of the option
  and save it into struct osnoise_context's orig_<opt> field,
- osnoise_set_<opt>() - to set the value of the option requested by the
  user after reading and saving the original with osnoise_get_<opt>(),
  and save it into <opt> field of struct osnoise_context,
- osnoise_restore_<opt>() - restore the value recorded in orig_<opt>,
- static osnoise_put_<opt>() - restore the value recorded in orig_<opt>
  and update <opt> to reflect that.

The logic is duplicated for all the options, except for cpus (which is
the only string option) and period/runtime (which are handled together
and feature extra checks).

Deduplicate by moving the common code in get/set/restore/put into common
helper functions local to osnoise.c. The original set/restore/put
functions are reduced to wrappers generated using a set of X macros:

- OSNOISE_LL_OPTIONS, which invokes the OSNOISE_LL_OPTION macro for all
  "long long" options,
- OSNOISE_FLAG_OPTIONS, which invokes the OSNOISE_FLAG_OPTION macro for
  all flag options (boolean values in osnoise/options file).

Those are also used to auto-generate the corresponding fields in struct
osnoise_context, plus initialization and restoration code for them.

There are a few minor changes in the refactored code:

- osnoise_set_<opt>() now distinguishes between -2 (option cannot be
  set) and -1 (option not present in kernel) for all options.
- OSNOISE_OPTION_INIT_VAL and OSNOISE_TIME_INIT_VAL are removed and
  replaced with a plain -1; all unsigned long long fields are changed to
  signed long long, consistent with pre-existing "%lld" format string in
  osnoise_write_ll_config().
- osnoise_restore_<opt>() now correctly resets the <opt> field (not
  orig_<opt>) for all options.

The change is intended to simplify adding and modifying tracer options.
It also makes the code shorter by a bit over 500 lines.

Assisted-by: Claude:claude-opus-4-6
Link: https://lore.kernel.org/r/20260929142944.1841462-1-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>