ext4: choose hardlimit when softlimit is larger than hardlimit in ext4_statfs_project()

Setting softlimit larger than hardlimit seems meaningless
for disk quota but currently it is allowed. In this case,
there may be a bit of comfusion for users when they run
df comamnd to directory which has project quota.

For example, we set 20M softlimit and 10M hardlimit of
block usage limit for project quota of test_dir(project id 123).

[root@hades mnt_ext4]# repquota -P -a
*** Report for project quotas on device /dev/loop0
Block grace time: 7days; Inode grace time: 7days
                        Block limits                File limits
Project         used    soft    hard  grace    used  soft  hard  grace
----------------------------------------------------------------------
 0        --      13       0       0              2     0     0
 123      --   10237   20480   10240              5   200   100

The result of df command as below:

[root@hades mnt_ext4]# df -h test_dir
Filesystem      Size  Used Avail Use% Moun...