IME: Fix Happened IllegalArgumentException 315 times during monkey test

The method startInputInnerLocked() sometimes throw IllegalArgument
Exception. There are 3 places invoked this method, but one of them
forgot to catch this exception.

Catch the IllegalArgumentException when invoke startInputInnerLocked().

CRs-Fixed: 563388

Change-Id: I315cb46b1d16c2862989cb9c0c10ed6613884522