HID: hidraw: fix hidraw_disconnect()

hidraw_disconnect() first sets an entry in hidraw_table to NULL
and calls device_destroy() afterwards. The thereby called
hidraw_release() tries to read this already cleared value resulting
in never removing any device from the list.
This got fixed by changing the order of events.

Signed-off-by: Stefan Achatz <erazor_de@users.sourceforge.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>