kfdtest: finetune MMBench subtest criteria

Change the proportion to 6/10 on APUs.

Change-Id: I3576cb23d0f14ff6d576a5db4bdeef9446aa10d2
Signed-off-by: Yifan Zhang <yifan1.zhang@amd.com>

tests/kfdtest/src/KFDMemoryTest.cpp

@@ -963,9 +963,13 @@ TEST_F(KFDMemoryTest, MMBench) {
             memFlags.ui32.NonPaged = 1;
 
             /* Buffer sizes are 2MB aligned to match new allocation policy.
-             * Upper limit of buffer number to fit 80% vram size.
+             * Upper limit of buffer number to fit 80% vram size. APUs w/
+			 * smaller VRAM needs different criteria.
              */
-            bufLimit = ((vramSizeMB << 20) * 8 / 10) / ALIGN_UP(bufSize, VRAM_ALLOCATION_ALIGN);
+            if (vramSizeMB <= 512)
+                bufLimit = ((vramSizeMB << 20) * 6 / 10) / ALIGN_UP(bufSize, VRAM_ALLOCATION_ALIGN);
+            else
+                bufLimit = ((vramSizeMB << 20) * 8 / 10) / ALIGN_UP(bufSize, VRAM_ALLOCATION_ALIGN);
 
             if (bufLimit == 0)
                 continue; // skip when bufSize > vram