va.h: TopFieldOrderCnt/BottomFieldOrderCnt should be signed instead of unsigned

POC should be integer.

Change-Id: I75281aafa148c88f0de58981969e1c43ea8d2684
Signed-off-by: ywan171 <yi.a.wang@intel.com>

va/va.h

@@ -1038,8 +1038,8 @@ typedef struct _VAPictureH264
     VASurfaceID picture_id;
     unsigned int frame_idx;
     unsigned int flags;
-    unsigned int TopFieldOrderCnt;
-    unsigned int BottomFieldOrderCnt;
+    signed int TopFieldOrderCnt;
+    signed int BottomFieldOrderCnt;
 } VAPictureH264;
 /* flags in VAPictureH264 could be OR of the following */
 #define VA_PICTURE_H264_INVALID			0x00000001