usb: dwc3: gadget: Prevent repeat pullup()

Don't do soft-disconnect if it's previously done. Likewise, don't do
soft-connect if the device is currently connected and running. It would
break normal operation.

Currently the caller of pullup() (udc's sysfs soft_connect) only checks
if it had initiated disconnect to prevent repeating soft-disconnect. It
doesn't check for soft-connect. To be safe, let's keep the check here
regardless whether the udc core is fixed.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/1c1345bd66c97a9d32f77d63aaadd04b7b037143.1650593829.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>