Small updates:

  - don't try chiprev 0100 erratum 0114 workaround on
    newer chips; and (mostly) revert it when clearing
    endpoint halt feature.  (bugfix)

  - add missing define for the "force crc error" bit;
    I guess those #defines were generated from old chip
    specs!  potentially useful with test software.

  - sysfs register dump includes chiprev and decodes some
    of the more interesting endpoint response bits.

  - makes a sysfs "gadget" node, representing the gadget
    itself.  (decided against the class_device or bus_type
    approaches, until their value outweighs their costs.)