libs: encoder: h264fei: don't free memory on stack

libs: encoder: h264fei: don't free memory on stack

Issue detected by Coverity

`info_to_pak` variable in gst_vaapi_encoder_h264_fei_encode() is
declared in the stack, but it is free in
gst_vaapi_feienc_h264_encode() as if declared on the heap.

This patch initializes the structure and removes the free.

A non-heap pointer is placed on the free list, likely causing a crash
later.

In gst_vaapi_encoder_h264_fei_encode: Free of an address-of
expression, which can never be heap allocated.