Update documenation for DATA_REGISTRATION_STATE

Be specific on the formats supported for the LTE information.

Bug: 7651566
Change-Id: I553b3e3ea8005ede2da121950626c9584f74f234
Merge tag 'android-4.2.2_r1' of https://android.googlesource.com/platform/hardware/ril into 1.1

Android 4.2.2 release 1