VAAPI: Enabled deinterlacing code.

I have still yet to see any actual VAAPI deinterlacing but allow it just
in case.

If deinterlacing does not work for you, please ensure you don't set the
main deinterlacer to Bob (2x) as this will double the frame rate for
zero benefit.

mythtv/libs/libmythtv/vaapicontext.cpp

@@ -621,14 +621,10 @@ bool VAAPIContext::CopySurfaceToTexture(const void* buf, uint texture,
         return false;
 
     int field = VA_FRAME_PICTURE;
-    //if (scan == kScan_Interlaced)
-    //    field = VA_TOP_FIELD;
-    //else if (scan == kScan_Intr2ndField)
-    //    field = VA_BOTTOM_FIELD;
-
-    //INIT_ST;
-    //va_status = vaSyncSurface(m_ctx.display, surf->m_id);
-    //CHECK_ST;
+    if (scan == kScan_Interlaced)
+        field = VA_TOP_FIELD;
+    else if (scan == kScan_Intr2ndField)
+        field = VA_BOTTOM_FIELD;
 
     INIT_ST;
     va_status = vaCopySurfaceGLX(m_ctx.display, glx_surface, surf->m_id, field);