ENGR00217719 usb gadget msc may enumeration fail if msc storage response slow

ENGR00217719 usb gadget msc may enumeration fail if msc storage response slow

- communication between the usb driver and msc class driver is using
  raise_exception/handle_excpetion, such mechaism can only have two
  events(exceptions) at most, one is on processing and another is store to be
  executed after the current one completed.
  If the first one processing is very slow, and the third one occur, then the
  second one will be overwriten by the third one and then the second event is
  lost and then enumeration failed
- since it is the linux community code, it is hard to change the whole frame
  work, currently only a work around is provided
- because this issue is brought in when the first reset event, when this
  event occur, a lun sync will happen and it will cost much time, but in fact
  this lun sync is not necessary for the first reset event, the work around
  is to skip this lun sync.

Signed-off-by: Tony LIU <junjie.liu@freescale.com>