[idd] driver: use the frameSize instead of the resource size

As the resource size can be larger then the actual frame data, we
need to track this seperately so that we don't waste cycles copying
data the client will never use.

idd/LGIdd/CFrameBufferResource.cpp

@@ -12,7 +12,10 @@ bool CFrameBufferResource::Init(CSwapChainProcessor * swapChain, uint8_t * base,
 
   // nothing to do if the resource already exists and is large enough
   if (m_base == base && m_size >= size)
+  {
+    m_frameSize = size;
     return true;
+  }
 
   Reset();
 
@@ -87,9 +90,10 @@ bool CFrameBufferResource::Init(CSwapChainProcessor * swapChain, uint8_t * base,
 
   m_res->SetName(resName);
 
-  m_base  = base;
-  m_size  = size;
-  m_valid = true;
+  m_base      = base;
+  m_size      = size;
+  m_frameSize = size;
+  m_valid     = true;
   return true;
 }