f2fs: change get_new_data_page to pass a locked node page

This patch is for passing a locked node page to get_dnode_of_data.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --cc fs/f2fs/data.c
Simple merge

diff --cc fs/f2fs/dir.c
Simple merge

diff --cc fs/f2fs/f2fs.h
Simple merge

diff --cc fs/f2fs/file.c
Simple merge