Allow DO/PO to go back to normal permission state.

We have APIs for a DO/PO to fix a permission in a granted or
denied state in which the user cannot manage this permission
through the UI. However, there is no way to go back to the
default state in which the user gets to choose the permission
grant state.

Change-Id: I2562a1d8b1385cd740b44812844ef14c895c2902