AMSv2: don't reboot on USB plug

Users will have to reboot to OF manually or to power off, and then plug USB
No message is displayed because usb_detect() is run from a tick

This lacks documentation but should be OK for Unstable devices, and
will hopefully prevent clueless users from opening their devices and
breaking them definitely, instead of waiting for the battery to power
off.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27837 a1c6a512-1295-4272-9138-f99709370657

firmware/target/arm/as3525/usb-as3525.c

@@ -55,5 +55,11 @@ void usb_remove_int(void)
 
 int usb_detect(void)
 {
+#if CONFIG_CPU == AS3525v2
+    /* Rebooting on USB plug can crash these players in a state where
+     * hardware power off (pressing the power button) doesn't work anymore
+     * TODO: Implement USB in rockbox for these players */
+    return USB_EXTRACTED;
+#endif
     return usb_status;
 }