Fix phone account comparison in Telecom dumpsys.

When telecom state is dumped prior to the user choosing a phone account,
the target phone account and delegate phone account are null, causing an
NPE.
Using Objects.equals fixes that.  Derp.

Test: Manual testing using adb shell dumpsys telecom
Fixes: 160001860
Change-Id: I9bee724026f2484a63fb46331e72982a3e5f5a5b