prima_wlan: workaround: fix unload errir prima_wlan.ko

Revert sched: Fix race in task_group()
http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=commit;h=64ac72f81b1b41819dab596d1524bd5cae4813fd
Linux kernel 3.0.47
Linux kernel 3.0.48
Linux kernel 3.0.49
Linux kernel 3.0.50
Linux kernel 3.0.51
Linux kernel 3.0.52
Linux kernel 3.0.53
Linux kernel 3.0.54
Linux kernel 3.0.55
Linux kernel 3.0.56
Linux kernel 3.0.57
Linux kernel 3.0.58
Linux kernel 3.0.59