cl-bayer: fix 3a-stats calculation
cl-bayer: fix 3a-stats calculation

 * reduce sum on 3a-stats may get wrong index if l_id_x + count larger
   than STATS_3A_GRID_SIZE which is not the buf-pitch

Signed-off-by: Wind Yuan <d3b25194a13defcddf619d66a03bde7d96f8d487@intel.com>

skibey/libxcam,skibey/libxcam,dspmeng/libxcam,skibey/libxcam,dspmeng/libxcam,dspmeng/libxcam