lavc/vaapi_encode_h265: fix conf_win_xxx_offset for 4:2:2/4:4:4 encoding

lavc/vaapi_encode_h265: fix conf_win_xxx_offset for 4:2:2/4:4:4 encoding

Use desc->log2_chroma_w/h to calculate the sps->conf_win_right/bottom_offset.

Based on Table 6-1, SubWidthC and SubHeightC depend on chroma format(log2_chroma_w/h).

Based on D-28 and D-29, set the correct cropped width/height.

croppedWidth  = pic_width_in_luma_samples −
                SubWidthC * ( conf_win_right_offset + conf_win_left_offset );

croppedHeight = pic_height_in_luma_samples −
                SubHeightC * ( conf_win_bottom_offset + conf_win_top_offset );

Signed-off-by: Linjie Fu <linjie.fu@intel.com>