These two functions do almost the same thing and duplicate some code.
Merge their implementation into a single common function.
res_counter_charge_locked() takes one more parameter but it doesn't seem
to be used outside res_counter.c yet anyway.

There is no (intended) change in the behaviour.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NGlauber Costa <glommer@parallels.com>
Acked-by: NKirill A. Shutemov <kirill@shutemov.name>
Cc: Li Zefan <lizefan@huawei.com>