Here is a patch that fixes the disconnect handling and locking for the
vicam driver. It does the following.

1.)	Change the parameters of send_control_msg to take a struct
	vicam_camera instead of struct usb_device to allow for locking
	of the device. Note that __send_control_msg does not lock the
	camera. send_control_msg locks the camera before calling
	__send_control_msg.
2.)	Remove all instances of busy_lock. busy_lock was renamed to
	cam_lock and used to lock out simultaneous uses of the camera
	and handle disconnects. We may want to add back a different lock
	to handle smp type stuff.
3.)	Separate read_frame and vicam_decode_color. This should move us
	along toward asynchronous urbs.

This patch does not address the locking of the camera that is still
needed by the proc interface.