mm/migrate: fix comment typo syncronous->synchronous

Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/migrate.c b/mm/migrate.c
index 3bbaf5d..c87ef92 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -736,7 +736,7 @@
 
 	if (PageWriteback(page)) {
 		/*
-		 * Only in the case of a full syncronous migration is it
+		 * Only in the case of a full synchronous migration is it
 		 * necessary to wait for PageWriteback. In the async case,
 		 * the retry loop is too short and in the sync-light case,
 		 * the overhead of stalling is too much