Updated the description to use the TelephonyCallback API.

Updated the description to use the TelephonyCallback API
instead of deprecated the PhoneStateListener.
The PhoneStateListeners have been deprecated in API31,
but the description still guides the use of it. So have
updated the description to use the TelephonyCallback API
instead.

Bug: 315801330
Test: build
Change-Id: I2c4df36a7be79b88c906b326489e00205ec92d67
1 file changed