fs_config.c: Remove obsolete reference to /system/bin/pppd-ril

Codesearch finds no reference to this in the Android tree. It was
added in 2010 in commit bbf1c64527dde837a236b4d6b9f75343adbca119.

Change-Id: I8cd1153912b78b4b23b8f5ba2577a58c5c49e316
1 file changed