ceph: add additional size check in ceph_setattr()

ceph_setattr() finally calls vfs function inode_newsize_ok()
to do offset validation and that is based on sb->s_maxbytes.
Because we set sb->s_maxbytes to MAX_LFS_FILESIZE to through
VFS check and do proper offset validation in cephfs level,
we need adding proper offset validation before calling
inode_newsize_ok().

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>