Fix NullPointerException when phone number cannot got

Fix the NullPointerException caused by null phone number got from
TelephonyManager when eSIM is enabled. This exception will cause the
whole settings crash.

Test: manual test
Bug: 37246921
Change-Id: I4d0f8f085f70ed3248d1db3bd7a7ff6e199230b9
2 files changed