Silence warning about unused variables in BRILLO.

This patch moves the call to validateClientPermissionsLocked() outside
the #if so it is executed in Brillo builds anyway, but the result is
ignored. This fixes the warning about unused parameters which was
causing the build to fail.

Bug: 31068444
Test: `make dist` in Brillo

Change-Id: I8a6648bf2221406068c9f5a1850a59ae0bde03ca