drm/amdgpu/display: Address kdoc for 'is_psr_su' in 'fill_dc_dirty_rects'

The is_psr_su parameter is a boolean flag indicating whether the Panel
Self Refresh Selective Update (PSR SU) feature is enabled which is a
power-saving feature that allows only the updated regions of the screen
to be refreshed, reducing the amount of data that needs to be sent to
the display.

Fixes the below with gcc W=1:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:5257: warning: Function parameter or member 'is_psr_su' not described in 'fill_dc_dirty_rects'

Fixes: d16df040 ("drm/amdgpu: make damage clips support configurable")
Cc: stable@vger.kernel.org
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -5235,6 +5235,10 @@ static inline void fill_dc_dirty_rect(struct drm_plane *plane,
  * @new_plane_state: New state of @plane
  * @crtc_state: New state of CRTC connected to the @plane
  * @flip_addrs: DC flip tracking struct, which also tracts dirty rects
+ * @is_psr_su: Flag indicating whether Panel Self Refresh Selective Update (PSR SU) is enabled.
+ *             If PSR SU is enabled and damage clips are available, only the regions of the screen
+ *             that have changed will be updated. If PSR SU is not enabled,
+ *             or if damage clips are not available, the entire screen will be updated.
  * @dirty_regions_changed: dirty regions changed
  *
  * For PSR SU, DC informs the DMUB uController of dirty rectangle regions