Dump UiccController's physical <-> logical slot mapping.

This can usually be deduced from mUiccSlots[*].mUiccCard.mPhoneId, but
things aren't always clear when nulls are present. Dumping the mapping
explicitly also cleans things up slightly for interested parsing tools.

Test: make, dumpsys TelephonyDebugService
Bug: 174493665
Change-Id: I2f083a9b37181d212186653461fa5616e8df9fae