mm/page_counter: correct the obsolete func name in the comment of page_counter_try_charge()

Since commit bbec2e15 ("mm: rename page_counter's count/limit into
usage/max"), page_counter_limit() is renamed to page_counter_set_max().
So replace page_counter_limit with page_counter_set_max in comment.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lkml.kernel.org/r/20200917113629.14382-1-linmiaohe@huawei.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_counter.c

@@ -109,7 +109,7 @@ bool page_counter_try_charge(struct page_counter *counter,
 		 *
 		 * The atomic_long_add_return() implies a full memory
 		 * barrier between incrementing the count and reading
-		 * the limit.  When racing with page_counter_limit(),
+		 * the limit.  When racing with page_counter_set_max(),
 		 * we either see the new limit or the setter sees the
 		 * counter has changed and retries.
 		 */