Add Galaxy Tab 2 7" Support

Device: Galaxy Tab 2 7"
Models: P3100 & P3110

Device trees:
P3100: https://github.com/Chirag-Galani/android_device_samsung_p3100
P3110: https://github.com/Chirag-Galani/android_device_samsung_p3110

XDA Thread: http://forum.xda-developers.com/showthread.php?t=2589352