Remove char state cache.

Removes charpool which caches char state objects to be reused. This
charpool was causing char state objects to duplicate.

Fixes: 265978605
Test: open pin and spam enter to reset pin and spam pin numbers. I
eventually get a duplicate. I also logged the char state array to
confirm that the same char state object is being added in append.

Change-Id: I9724fcf8d29d43069e298bb0407cea90405741b7