usb: gadget: aspeed: Don't set port enable change bit on reset

This bit should be only set when the port enable goes down, for
example, on errors. Not when it gets set after a port reset. Some
USB stacks seem to be sensitive to this and fails enumeration.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>