drm/xe/rtp: Drop sentinels from arg to xe_rtp_process_to_sr()

There's a mismatch on API: while xe_rtp_process_to_sr() processes
entries until an entry without name, the active tracking with
xe_rtp_process_ctx_enable_active_tracking() needs to use the number of
elements. The number of elements is taken everywhere using ARRAY_SIZE(),
but that will have one entry too many. This leads to the following
warning, as reported by lkp:

   drivers/gpu/drm/xe/xe_tuning.c: In function 'xe_tuning_dump':
>> include/drm/drm_print.h:228:31: warning: '%s' directive argument is null [-Wformat-overflow=]
     228 |         drm_printf((printer), "%.*s" fmt, (indent), "\t\t\t\t\tX", ##__VA_ARGS__)
         |                               ^~~~~~
   drivers/gpu/drm/xe/xe_tuning.c:226:17: note: in expansion of macro 'drm_printf_indent'
     226 |                 drm_printf_indent(p, 1, "%s\n", engine_tunings[idx].name);
         |                 ^~~~~~~~~~~~~~~~~

That's because it will still process the last entry when tracking the
active tunings. The same issue exists in the WAs. Change
xe_rtp_process_to_sr() to also take the number of elements so the empty
entry can be removed and the warning should go away. Fixing on the
active-tracking side would more fragile as the it would need a `- 1`
everywhere and continue to use a different approach for number of
elements.

Aside from the warning, it's a non-issue as there would always be enough
bits allocated and the last entry would never be active since
xe_rtp_process_to_sr() stops on the sentinel.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202503021906.P2MwAvyK-lkp@intel.com/


Cc: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306-fix-print-warning-v1-1-979c3dc03c0d@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>