- Remove an oops in the queue fault cleanup path, caused by using the
   wrong giveback routine (heavy weight vs lighter-weight).  Move a few
   key bits of code into that lighter weight version.

 - Trigger that lighter-weight cleanup during URB completion, when the
   URB in question can't yet been handed off to the hardware even if
   it's at the queue head.

 - Reduce syslog noise when those fault cleanup paths are triggered from
   scatterlist calls by usb-storage.

 - Paranoia: when scheduling, insist that the endpoint fifo isn't smaller
   than required.

Oops observed courtesy of a slightly flakey usb-storage device, which
once again proves itself handy for testing.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>