Revert "Kantjer: Fix for exFat sdcards"

This reverts commit 5a8b7e964a1ff41a315ded50ca598d552ca96d13.
Compile with -Os to fix broken exfat

Thanks to @kantjer for his idea that the exfat problem lies on mount.exfat

Change-Id: Ic6492b16452960f6fb0a6a8c5f00fa7e022125d5