f2fs: clear PageError on writepage

Cherry-pick from origin/upstream-f2fs-stable-linux-4.4.y:
commit 070da800 ("f2fs: clear PageError on writepage")

This patch clears PageError in some pages tagged by read path, but when we
write the pages with valid contents, writepage should clear the bit likewise
ext4.

Change-Id: I7272074f2bb9c81fc43e37074b44e9d761756263
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>