Try-catch for deletePreferredApnId()

Devices pre-dating lollipop have pref apn stored in shared pref
without sub id. That shared pref was removed in M, but devices
skipping M will run into this crash on trying to extract sub id
from the pref apn key.

Bug: 25587618
Change-Id: I5a7727acd390fe861a8bb71a0a6eab8246791c59
1 file changed