Revert "usb: gadget: storage: Remove warning message"

This reverts commit e70b3f5d.

EJ writes:
	Thinh found this patch might cause a failure in USB CV TD 9.13
	Set Configuration Test. We are trying to fix it.  Could you
	please defer the merging of this patch until we fix it?

So am now dropping it.

Reported-by: EJ Hsu <ejh@nvidia.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>