Don't show FST size in game properties

Normal users don't care about it. In fact, people care so
little about it that the Wii implementation of it was broken
starting from when it was implemented (eb65601) to 7 years
later (e0a47c1), apparently without anyone reporting it.

Source/Core/DiscIO/VolumeGC.cpp

@@ -138,15 +138,6 @@ std::vector<u32> CVolumeGC::GetBanner(int* width, int* height) const
   return m_image_buffer;
 }
 
-u64 CVolumeGC::GetFSTSize(const Partition& partition) const
-{
-  u32 size;
-  if (!Read(0x428, 0x4, (u8*)&size, partition))
-    return 0;
-
-  return Common::swap32(size);
-}
-
 std::string CVolumeGC::GetApploaderDate(const Partition& partition) const
 {
   char date[16];