usb: cdns3: gadget: sg_support is only for DEV_VER_V2 or above

The scatter buffer list support earlier than DEV_VER_V2 is not
good enough, software can't know well about short transfer for it.

Cc: Pawel Laszczak <pawell@cadence.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>