tests: Modify vkMapMemory calls to use VK_WHOLE_SIZE

Calls were still using zero to map entire allocation which caused validation issues.
diff --git a/tests/init.cpp b/tests/init.cpp
index 1bb1d31..b694112 100644
--- a/tests/init.cpp
+++ b/tests/init.cpp
@@ -160,7 +160,7 @@
     err = vkAllocateMemory(device(), &alloc_info, NULL, &gpu_mem);
     ASSERT_VK_SUCCESS(err);
 
-    err = vkMapMemory(device(), gpu_mem, 0, 0, 0, (void **) &pData);
+    err = vkMapMemory(device(), gpu_mem, 0, VK_WHOLE_SIZE, 0, (void **) &pData);
     ASSERT_VK_SUCCESS(err);
 
     memset(pData, 0x55, alloc_info.allocationSize);