usb: dwc3: gadget: Disable Vendor Test LMP Received event

Some users questioned why Vendor Test LMP Received event was enabled.
The driver currently doesn't handle this event. Let's disable it to
avoid confusion.

Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/4e785ba5d5e95801b6fcf96116f6090216e70760.1610596478.git.Thinh.Nguyen@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>