App ops was never meant to have been included in any android firmware for general users. Sony have probably removed any links to it by order of Google. The only way I can think to restore it is to downgrade back to 15.4.A.0.23.
My Phone: Sony Xperia M C1905 | ROM: Modified Stock | Base Firmware/Build Number: 15.4.A.0.23 | Android Version: 4.3 | Kernel: Stock (Permanently Locked Bootloader) | Network: GiffGaff
My Tablet: Google Nexus 7 (2012) | ROM: CM11 | Base Firmware/Build Number: 11-20140527-NIGHTLY-grouper | Android Version: 4.4.4 | Kernel: CM11 | Network: N/A