init.qcom.usb: Rename target 'copper' to 'msm8974'

MSM target 'copper' is renamed to 'msm8974' starting with
Android JB release.

Change-Id: I536df1ef1d1af8d54a3f49b2b65b3688a8bd74d4

rootdir/etc/init.qcom.usb.sh

@@ -87,7 +87,7 @@ usb_config=`getprop persist.sys.usb.config`
 case "$usb_config" in
     "" | "adb") #USB persist config not set, select default configuration
         case $target in
-            "copper")
+            "msm8974")
                 setprop persist.sys.usb.config diag,adb
                 ;;
             "msm8960")