DUPLICATE FAT FILE NAMES

```
Description: "The NSH and POSIX API interpretations about sensitivity or
insensitivity to upper/lowercase file names seem to be not
consistent in our usage - which can result in creating two
directories with the same name..."

Example using NSH:

nsh> echo "Test1" >/tmp/AtEsT.tXt
nsh> echo "Test2" >/tmp/aTeSt.TxT
nsh> ls /tmp
/tmp:
AtEsT.tXt
aTeSt.TxT
nsh> cat /tmp/aTeSt.TxT
Test2
nsh> cat /tmp/AtEsT.tXt
Test1

Status: Open
Priority: Low
```