drm/amd/display: use FB pitch to fill dc_cursor_attributes

Instead of relying on pitch (in pixels) == width, use the FB pitch. This
is less confusing to readers, and works correctly if we ever support FBs
with a pitch (in pixels) != width.

This also makes the code symmetrical with fill_plane_buffer_attributes.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -7438,7 +7438,7 @@ static void handle_cursor_update(struct drm_plane *plane,
 	attributes.rotation_angle    = 0;
 	attributes.attribute_flags.value = 0;
 
-	attributes.pitch = attributes.width;
+	attributes.pitch = afb->base.pitches[0] / afb->base.format->cpp[0];
 
 	if (crtc_state->stream) {
 		mutex_lock(&adev->dm.dc_lock);