[2/n] Refactor CPU copies

- move blocking flag to command queue function
- refactor buffer function for better readability
- add new method to easily state that buffer is compressed.

Change-Id: I62465b7bc8b109f14d0012b5641d4b822e3cc908
Signed-off-by: Michal Mrozek <michal.mrozek@intel.com>

runtime/command_queue/command_queue.cpp

@@ -562,12 +562,23 @@ bool CommandQueue::bufferCpuCopyAllowed(Buffer *buffer, cl_command_type commandT
         return false;
     }
 
-    if (debugVariableSet && buffer->getGraphicsAllocation()->getAllocationType() != GraphicsAllocation::AllocationType::BUFFER_COMPRESSED) {
+    //if buffer is compressed we cannot do CPU copy
+    if (buffer->isCompressed()) {
+        return false;
+    }
+
+    if (debugVariableSet) {
         return true;
     }
 
+    //non blocking transfers are not expected to be serviced by CPU
+    //we do not want to artifically stall the pipeline to allow CPU access
+    if (blocking == CL_FALSE) {
+        return false;
+    }
+
     //check if buffer is compatible
-    if (!buffer->isReadWriteOnCpuAllowed(blocking, ptr, size)) {
+    if (!buffer->isReadWriteOnCpuAllowed(ptr, size)) {
         return false;
     }