usb/isp1760: Fix problems that trigger WARNING at line 1136.

1) A bug in the usage of time_after() in errata2_function().

2) Clear done_maps just prior to starting a new transfer in
   start_bus_transfer(), instead of just after, when done_map bits might have
   been validly set by the started transfer.

Signed-off-by: Arvid Brodin <arvid.brodin@enea.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>