core: Add back mistakenly removed string

    <!-- Shown in the lock screen to tell the user that their SIM/RUIM is locked and they must unlock it. -->

    <string name="lockscreen_sim_locked_message_cm">SIM/RUIM card is locked.</string>

    <!-- Displayed when a SIM PIN/PUK is entered incorrectly. -->

    <string name="pinpuk_attempts">\nAttempts remaining:</string>

    <!-- Displayed when the USSD/SS request is modified by STK CC to a

         different request. This will be displayed in a toast. -->

    <string name="stk_cc_ussd_to_dial">USSD request is modified to DIAL request.</string>