[vaapi] Support running progressive frames through the vpp deinterlacer

PAFF video requires to run all frames through the deinterlace filter
even if they are progressive. In that case, do not set any field flags
and only run one postprocessing step, producing one output picture.

xbmc/cores/VideoPlayer/DVDCodecs/Video/VAAPI.cpp

@@ -2588,7 +2588,7 @@ bool CVppPostproc::Filter(CVaapiProcessedPicture &outPic)
 
   // skip deinterlacing cycle if requested
   if ((m_step == 1) &&
-      ((outPic.DVDPic.iFlags & DVD_CODEC_CTRL_SKIPDEINT) || (m_vppMethod == VS_INTERLACEMETHOD_NONE)))
+      ((outPic.DVDPic.iFlags & DVD_CODEC_CTRL_SKIPDEINT) || !(outPic.DVDPic.iFlags & DVP_FLAG_INTERLACED) || (m_vppMethod == VS_INTERLACEMETHOD_NONE)))
   {
     Advance();
     return false;
@@ -2643,17 +2643,21 @@ bool CVppPostproc::Filter(CVaapiProcessedPicture &outPic)
   if (m_vppMethod != VS_INTERLACEMETHOD_NONE)
   {
     unsigned int flags = 0;
-    if (it->DVDPic.iFlags & DVP_FLAG_TOP_FIELD_FIRST)
-      flags = 0;
-    else
-      flags = VA_DEINTERLACING_BOTTOM_FIELD_FIRST | VA_DEINTERLACING_BOTTOM_FIELD;
 
-    if (m_step)
+    if (it->DVDPic.iFlags & DVP_FLAG_INTERLACED)
     {
-      if (flags & VA_DEINTERLACING_BOTTOM_FIELD)
-        flags &= ~VA_DEINTERLACING_BOTTOM_FIELD;
+      if (it->DVDPic.iFlags & DVP_FLAG_TOP_FIELD_FIRST)
+        flags = 0;
       else
-        flags |= VA_DEINTERLACING_BOTTOM_FIELD;
+        flags = VA_DEINTERLACING_BOTTOM_FIELD_FIRST | VA_DEINTERLACING_BOTTOM_FIELD;
+
+      if (m_step)
+      {
+        if (flags & VA_DEINTERLACING_BOTTOM_FIELD)
+          flags &= ~VA_DEINTERLACING_BOTTOM_FIELD;
+        else
+          flags |= VA_DEINTERLACING_BOTTOM_FIELD;
+      }
     }
     if (!CheckSuccess(vaMapBuffer(m_config.dpy, m_filter, (void**) &filterParams), "vaMapBuffer"))
     {