ext4: add read support for inline data

Let readpage and readpages handle the case when we want to read an
inlined file.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --cc fs/ext4/inline.c
Simple merge

diff --cc fs/ext4/inode.c
Simple merge

diff --cc fs/ext4/xattr.h
Simple merge