Revert "CHROMIUM: fuse: Implement CHROMEOS_TMPFILE"

6.1 kernels and later supports FUSE_TMPFILE and we no longer need to do our
local hack.

BUG=b:536947624,b:549808934
TEST=tast run arc.Boot.vm

This reverts commit f10cc3e1ac7c45b741722626fa3874f7312de855.

Change-Id: I9b89d18a03d84546474383b342d51bad89903d7c
Signed-off-by: Junichi Uekawa <uekawa@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/8255691
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
Tested-by: Junichi Uekawa <uekawa@chromium.org>
Commit-Queue: Junichi Uekawa <uekawa@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>