drm/atomic-helper: Add a note in drm_atomic_helper_reset_crtc() kernel-doc

As suggested in [0], add a note indicating that
drm_atomic_helper_reset_crtc() can be a no-op in some cases.

[0]:https://lore.kernel.org/all/Z7XfnPGDYspwG42y@phenom.ffwll.local/

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20250220140406.593314-1-herve.codina@bootlin.com
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>

Author: hcodina

drivers/gpu/drm/drm_atomic_helper.c

@@ -3409,6 +3409,10 @@ EXPORT_SYMBOL(drm_atomic_helper_disable_all);
  * This implies a reset of all active components available between the CRTC and
  * connectors.
  *
+ * NOTE: This relies on resetting &drm_crtc_state.connectors_changed.
+ * For drivers which optimize out unnecessary modesets this will result in
+ * a no-op commit, achieving nothing.
+ *
  * Returns:
  * 0 on success or a negative error code on failure.
  */