Staging: Pohmelfs: Sync fs before killing it, since dentry cache is shrunk...

Staging: Pohmelfs: Sync fs before killing it, since dentry cache is shrunk before writeback is invoked via generic_shutdown_super()

Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>