f2fs: use generic terms used for encrypted block management

This patch renames functions regarding to buffer management via META_MAPPING
used for encrypted blocks especially. We can actually use them in generic way.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 265c3bc..9e708e5 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -2528,8 +2528,7 @@ void f2fs_wait_on_page_writeback(struct page *page,
 	}
 }
 
-void f2fs_wait_on_encrypted_page_writeback(struct f2fs_sb_info *sbi,
-							block_t blkaddr)
+void f2fs_wait_on_block_writeback(struct f2fs_sb_info *sbi, block_t blkaddr)
 {
 	struct page *cpage;