SectorReader: Fix reading the last block of the disc.

Regression from PR #3795.

Source/Core/DiscIO/Blob.cpp

@@ -141,7 +141,7 @@ u32 SectorReader::ReadChunk(u8* buffer, u64 chunk_num)
 
 	// If we are reading the end of a disk, there may not be enough blocks to
 	// read a whole chunk. We need to clamp down in that case.
-	u64 end_block = GetDataSize() / m_block_size;
+	u64 end_block = (GetDataSize() + m_block_size - 1) / m_block_size;
 	if (end_block)
 		cnt_blocks = static_cast<u32>(std::min<u64>(m_chunk_blocks, end_block - block_num));