Fix a typo in an error message in InputMethodManagerService

This it a follow up CL to my previous CL [1], which introduced
EditorInfo#targetInputMethodUser.

There is a typo in Slog.e() message from
InputMethodManagerService#startInputOrWindowGainedFocusInternal() when
cross-user StartInput is requested without without
INTERACT_ACROSS_USERS_FULL permission.  This CL addresses the typo.

There should be no user-visible behavior change.

 [1]: Ia7ea944438d69669ccdf9111b34ba400e786a602
      0f5eade4

Bug: 120744418
Test: atest CtsInputMethodTestCases CtsInputMethodServiceHostTestCases
Change-Id: I09022bb225fb2e37ebf73218aedef9ab2503c53e