usb: dwc2: host: Support immediate retries for split transactions

In some cases, like when you've got a "Microsoft Wireless Keyboard 2000"
connected to dwc2 with a hub, expected that we'll get some transfer
errors sometimes.  The controller is expected to try at least 3 times
before giving up.  See figure "Figure A-67. Normal HS CSPLIT 3 Strikes
Smash" in the USB spec.

The dwc2 controller has a way to support this by using the "EC_MC"
field.  The Raspberry Pi driver has logic for setting this right.  See
fiq_fsm_queue_split_transaction() in their "dwc_otg_hcd.c".  Let's use
the same logic.

After making this change, we no longer get dropped characters from the
above mentioned keyboard.  Other devices on the same bus as the keyboard
also behave more properly.

Thanks for Julius Werner for the expert analysis and suggestions.

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>

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