usb: diag_bridge: Fix error handling during disconnect

usb_autopm_get_interface() returns an error if runtime PM is disabled,
yet this should not impede the ability to submit URBs. This can happen
just as the device is removed but the interface driver's disconnect()
routine has not been called. Thus any client wishing to call read or
write may errorneously continue to call and might eventually flood the
console with excessive printks which could cause a watchdog timeout. So
treat -EAGAIN and -EACCES as okay and only bail on other error values.

Also, rate-limit the printks associated with reading/writing on the
bridge to further avoid the possibility of excessive logging during
similar corner cases.

Finally, use -ENODEV as an indicator that read/write should halt. This
will handle the case when an URB fails to submit late in the device
disconnect stage, and the client should not attempt any more submissions.

CRs-fixed: 370694
Change-Id: Ia5f4a4bd7ed620eedd2cd00c117066b8c7eb4f8c
Signed-off-by: Jack Pham <jackp@codeaurora.org>