Evidently some wacky USB-ATA bridges don't recognize the SYNCHRONIZE
CACHE command, as shown in this email thread:

	http://marc.info/?t=138978356200002&r=1&w=2

The fact that we can't tell them to drain their caches shouldn't
prevent the system from going into suspend.  Therefore sd_sync_cache()
shouldn't return an error if the device replies with an Invalid
Command ASC.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Reported-by: NSven Neumann <s.neumann@raumfeld.com>
Tested-by: NDaniel Mack <zonque@gmail.com>
CC: <stable@vger.kernel.org>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>