rescounter: remove __must_check from res_counter_charge_nofail()

Since we will succeed with the allocation no matter what, there isn't a
need to use __must_check with it. It can very well be optional.

Signed-off-by: Glauber Costa <[e-mail]>
Signed-off-by: KAMEZAWA Hiroyuki <[e-mail]>
Cc: Aneesh Kumar K.V <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Frederic Weisbecker <[e-mail]>
Cc: Ying Han <[e-mail]>
Reviewed-by: Tejun Heo <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/res_counter.h

···
 					   unsigned long val, bool force);
 int __must_check res_counter_charge(struct res_counter *counter,
 		unsigned long val, struct res_counter **limit_fail_at);
-int __must_check res_counter_charge_nofail(struct res_counter *counter,
+int res_counter_charge_nofail(struct res_counter *counter,
 		unsigned long val, struct res_counter **limit_fail_at);
 
 /*