staging: exfat: fix fs_sync() calls.

The majority of them were totally backwards.  Change the logic
so that if DELAYED_SYNC *isn't* in the config, we actually flush to disk
before flagging the file system as clean.

That leaves two calls in the DELAYED_SYNC case.  More detailed
analysis is needed to make sure that's what's really needed, or if other
call sites also need a fs_sync() call.  This patch is at least "less wrong"
than the code was, but further changes should be another patch.

Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>

Link: https://lore.kernel.org/r/11092.1570043784@turing-police


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>