Squashed revert of exfat

Revert "exfat: make it built-in"

This reverts commit bd20674c1bb59f3020e5e058ee79d7697a4291b8.

Revert "exfat driver from samsung open source"

This reverts commit 4391578747074fa85cd69a61ee0ab69dbb29dc80.

Change-Id: If770ad272968b7208634acec73bd1e01fae59e2e