Remove NfcFragment from activity when no longer sharing.
Remove NfcFragment from activity when no longer sharing.

This fixes scenarios where the same activity sets, unsets
and re-sets an NdefMessage and/or callback.

Bug: 5454848
Change-Id: I5ed98047b9cfe90d2f48656d978f2d08bb4bf0cc

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base