Just update your PC Android SDK to API Level 16 or latest
Android 4.2.2 brought up this limitation owing to security breach by ADB-Savy
To enable ADB on your PC, Update your Android SDK-r16 or LATEST, Update the system path for Platform tools --> Execute ADB cdevices command --> check the Device --> Tap Allow on Pop-up. Thats it!
Android Dev site comments :
"When you connect a device running Android 4.2.2 or higher to your computer, the system shows a dialog asking whether to accept an RSA key that allows debugging through this computer. This security mechanism protects user devices because it ensures that USB debugging and other adb commands cannot be executed unless you're able to unlock the device and acknowledge the dialog. This requires that you have adb version 1.0.31 (available with SDK Platform-tools r16.0.1 and higher) in order to debug on a device running Android 4.2.2 or higher."