cache_free_buffers() was only used in the file deletion and unload, and
the file is also freed after that, so here we combine the cache free and
file free together and do the cache free in the cache thread.
Change-Id: I57e9a27c9a6467bcf6c85cd277db3b57e06c98e5
Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/1795
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>