init.qcom.usb: set default composition for ferrum

Set DIAG + ADB as default USB composition for ferrum. It will be
changed later to support other interfaces like modem and rmnet.

Change-Id: I9ceb305d917d61117b63d9cdc78b884f4307b8ac

rootdir/etc/init.qcom.usb.sh

@@ -148,6 +148,9 @@ case "$usb_config" in
                         "msm8994")
                             setprop persist.sys.usb.config diag,serial_smd,serial_tty,rmnet_ipa,mass_storage,adb
                         ;;
+			"ferrum")
+				setprop persist.sys.usb.config diag,adb
+			;;
                         *)
                             setprop persist.sys.usb.config diag,serial_smd,serial_tty,rmnet_bam,mass_storage,adb
                         ;;