Use IEC units in app info data usage.

Settings > Apps & notifications > select some app that has done
some internet traffic.
Observe "Mobile data & Wi-Fi" summary data and take note of the
numbers. Then tap on it and observe that the numbers on the
details page don't match the one in the summary. This is because
the details use IEC units while the summary uses SI units.

This fix changes the summary to use IEC units too, removing
the discrepancy.

Bug: 137917003
Test: manually cause some traffic, see that the numbers are now
      consistent between the app info and usage details page

Change-Id: I4be5830d4e98a1c4739001c812e59d82415bf24a