The report lists all connected devices and gets updated when devices are
added or removed.
Example report:
<devices>
<device vendor_id="0x17ef" product_id="0x4816"/>
<device vendor_id="0x0a5c" product_id="0x217f"/>
<device vendor_id="0x8087" product_id="0x0020"/>
<device vendor_id="0x8087" product_id="0x0020"/>
<device vendor_id="0x1d6b" product_id="0x0002"/>
<device vendor_id="0x1d6b" product_id="0x0002"/>
</devices>
There is no distinction yet for multiple devices of the same type.
The report is named "devices" and an example policy for 'report_rom' would
look like:
<policy label="vbox -> usb_devices" report="usb_drv -> devices"/>
The report only gets generated if enabled in the 'usb_drv' configuration:
<config>
<raw>
<report devices="yes"/>
</raw>
</config>
Fixes#1506