[CodeClean] fix svace issue

[CodeClean] fix svace issue

1. change data type to handle gst-memory.
2. use util function to get nth tensor info.
3. add null-init in filter-edgetpu.
4. fix use-after-free case when parsing accel in tensor-filter.

Signed-off-by: Jaeyun Jung <jy1210.jung@samsung.com>