[alloctor]: add flags for alloctor

Each of the different alloctor has different alloctor modes,
such as allocating physical continuous memory, secure memory,
etc.

Change-Id: Ib032689f0cfd36b494843dcc176a22c6c9587b6a
Signed-off-by: Rimon Xu <rimon.xu@rock-chips.com>

osal/mpp_allocator_impl.h

@@ -23,6 +23,7 @@
 typedef struct MppAllocatorImpl_t {
     pthread_mutex_t lock;
     MppBufferType   type;
+    RK_U32          flags;
     size_t          alignment;
     os_allocator    os_api;
     void            *ctx;