usb:cdns3: Fix for CV CH9 running with g_zero driver.

Patch fixes issue with Halt Endnpoint Test observed during using g_zero
driver as DUT. Bug occurred only on some testing board.

Endpoint can defer transition to Halted state if endpoint has pending
requests.
Patch add additional condition that allows to return correct endpoint
status during Get Endpoint Status request even if the halting endpoint
is in progress.

Reported-by: Rahul Kumar <kurahul@cadence.com>
Signed-off-by: Rahul Kumar <kurahul@cadence.com>
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Fixes: 7733f6c3

 ("usb: cdns3: Add Cadence USB3 DRD Driver")
Tested-by: Roger Quadros <rogerq@ti.com>
Link: https://lore.kernel.org/r/1570430355-26118-1-git-send-email-pawell@cadence.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>