Changed a way to use device memory effectively.

Changed a way to use device memory effectively.

Divide device memory into small, medium and large size of buffer
to use the memory effectively when decoding many contexts.

In case of meta data such as width, height, framerate and etc,
each context uses 256byte memory region and utilizes the large size of memory
when copying video and audio buffer.

Change-Id: I37e111ec1540694d32380906132d79cd90a658ef
Signed-off-by: Kitae Kim <kt920.kim@samsung.com>