usb: dwc3: gadget: move AcceptU1Ena and AcceptU2Ena to Reset IRQ

According to the databook, the DWC3 Core will
reset those bits to 0 on USB Bus Reset. This
means we must re-enable those bits on every
reset interrupt.

Because we will always get a Reset interrupt
after loading a gadget driver, we can, instead
of re-enabling something that was just lost,
move the handling of those bits to the Reset
Interrupt.

This patch fixes USB30CV U1/U2 Test.

Signed-off-by: Gerard CAUVY <g-cauvy1@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>