frameworks/base: updates for camera HAL memory management

-- when the camera HAL allocates memory
	-- it requests is as N buffers by S bytes each
	-- it may specify a file descriptor to get mmapped; if -1, then we use ashmem
-- when issuing data and data-timestamp callbacks, the camera HAL specifies a
   buffer index
-- range checking is performed on the buffer indices
-- memory requested by a camera HAL is not incStrong'ed, and needs to be
   expliciftly released by the camera HAL (by calling the release method on the
   camera_memory_t handle)

Change-Id: I0f09603aa786c238590e7288388ab673787e6032
Signed-off-by: Iliyan Malchev <malchev@google.com>