BACKPORT: cgroup: use strlcpy() instead of strscpy() to avoid spurious warning

As long as cft->name is guaranteed to be NUL-terminated, using strlcpy() would
work just as well and avoid that warning, so the change below could be folded
into that commit.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
Change-Id: I8215beea12d94fda6a7834f8be6f8e0891285d0e
(cherry picked from commit 50034ed49645463a16327cad05694e201e6b4126)
Bug: 154548692
Signed-off-by: Marco Ballesio <balejs@google.com>
Signed-off-by: Alexander Winkowski <dereference23@outlook.com>