Fix an unintentional switch-case fall-through

This is a follow up CL to my previous CL [1], which introduced a
classical fall through bug due to a missing return statement.

 [1]: Ic614f112f960382280acd8891b3af56d47679f08
      ce82eb2d

Test: Manually made sure that calling
      InputConnection#performPrivateCommand() no longer causes
      IllegalStateException("Already recycled.").
Bug: 35079353
Fixes: 35681994
Change-Id: I9aa3c0497385e053718d829aad49495771b22b59