init scripts: fix initialization of management port

On some swtiches the management port was not accessible, most likely
for wrong timing in overall setup.  Removing and re-loading the
usb gadget module seems to fix the problem.

userspace/rootfs_override/etc/init.d/S01modules

 #!/bin/sh
 
 #for ttyGS0 console
-insmod /lib/modules/2.6.39/kernel/g_serial.ko
\ No newline at end of file
+insmod /lib/modules/2.6.39/kernel/g_serial.ko
+rmmod g_serial
+insmod /lib/modules/2.6.39/kernel/g_serial.ko