cgroup: Remove leftover instances of allow_attach

Fix:

kernel/sched/tune.c:718:2: error:
	unknown field ‘allow_attach’ specified in initializer
kernel/cpuset.c:2087:2: error:
	unknown field 'allow_attach' specified in initializer

Change-Id: Ie524350ffc6158f3182d90095cca502e58b6f197
Fixes: e78f134a ("CHROMIUM: remove Android's cgroup generic permissions checks")
Signed-off-by: Guenter Roeck <groeck@chromium.org>