PPC: set kMinimumCodeRangeSize in test-spaces/Regress3540 as multiple of PageSize

Setting kMinimumCodeRangeSize as 3*pagesize. This will set the
constant correctly for PPC where pagesize is 4MB.

R=mlippautz@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2206583004
Cr-Commit-Position: refs/heads/master@{#38450}

test/cctest/heap/test-spaces.cc

@@ -208,7 +208,7 @@ TEST(Regress3540) {
   TestMemoryAllocatorScope test_allocator_scope(isolate, memory_allocator);
   CodeRange* code_range = new CodeRange(isolate);
   size_t code_range_size =
-      kMinimumCodeRangeSize > 0 ? kMinimumCodeRangeSize : 3 * MB;
+      kMinimumCodeRangeSize > 0 ? kMinimumCodeRangeSize : 3 * Page::kPageSize;
   if (!code_range->SetUp(code_range_size)) {
     return;
   }