USB: usb-storage: don't clear-halt when Get-Max-LUN stalls

This patch (as1032) removes the Clear-Halt calls in
usb_stor_Bulk_max_lun().  Evidently some devices (such as the Oracom
MP3 player) really don't like to receive these requests when their
bulk endpoints aren't halted.

The only reason for adding them originally was to get an ancient
ZIP-100 drive to work.  But since this device has only a single LUN,
we don't need to send it a Get-Max-LUN request at all.  Adding an
unusual_devs entry for the ZIP-100 with the SINGLE_LUN flag set will
cause this step to be skipped.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>