HV:fix "Pointer param should be declared pointer to const"

Fix violations for function whose parameter can be read-only.

Tracked-On: #861
Signed-off-by: Huihuang Shi <huihuang.shi@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>

hypervisor/include/lib/mem_mgt.h

@@ -26,6 +26,6 @@ void *malloc(unsigned int num_bytes);
 void *calloc(unsigned int num_elements, unsigned int element_size);
 void *alloc_page(void);
 void *alloc_pages(unsigned int page_num);
-void free(void *ptr);
+void free(const void *ptr);
 
 #endif /* MEM_MGT_H */