Changed initial value of the parameter "enabled" to 1 for network, sound and
usb device plugins. Loading the plugin means that the user wants to enable it.
Disabling the device on the command line and in the config interface is still
possible.


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@12085 6c8e4198-a580-4521-a02f-c9ae86df1db9