Fix apparent possible memory overrun in processing_queue

Fix apparent possible memory overrun in processing_queue

The queue is a simple array of strings of size defined by:
  #define MAX_PROCESSING_OOPS 10
but the add_to / remove_from functions were hard coded to wrap the tail and
head array indices at 100.

Signed-off-by: Tim Pepper <timothy.c.pepper@linux.intel.com>