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

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 <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>