Added hipDeviceGetLimit api

1. hipDeviceGetLimit API for HCC path is added
2. Test for hipDeviceGetLimit API is added
3. The feature added only supports querying heap size
4. Corrected indents for malloc and free device functions
5. Removed redundant data structures
6. Added g_heap_malloc_size to store the heap size

Change-Id: If48d1b0ce9270e994f1c542cc283ddbb14746bbb

tests/src/deviceLib/hipTestDeviceLimit.cpp

@@ -0,0 +1,10 @@
+#include<hip/hip_runtime_api.h>
+#include<iostream>
+#include<assert.h>
+
+int main()
+{
+    size_t heap;
+    assert(hipSuccess == hipDeviceGetLimit(&heap, hipLimitMallocHeapSize));
+    assert(heap == 4194304);
+}