Adjust the passing value for GPU agent when do max single allocation test

For APU asics, the default configuration size of video memory is
relatively small, plus the reserved region, ratio of max alloc size to
the pool size may below the expected value, so adjust it.

Change-Id: I798b44d9532aa6a381a1cc19faa5a46110bf0ad6


[ROCm/ROCR-Runtime commit: df59bfd57b]

projects/rocr-runtime/rocrtst/suites/functional/memory_basic.cc

@@ -233,7 +233,7 @@ void MemoryTest::MaxSingleAllocationTest(hsa_agent_t ag,
   }
 
   if (ag_type == HSA_DEVICE_TYPE_GPU) {
-    EXPECT_GE((float)max_alloc_size/pool_sz, (float)15/16);
+    EXPECT_GE((float)max_alloc_size/pool_sz, (float)7/8);
   }
   if (verbosity() > 0) {
     std::cout << kSubTestSeparator << std::endl;