usb: cdns2: Fix controller reset issue

Patch fixes the procedure of resetting controller.
The CPUCTRL register is write only and reading returns 0.
Waiting for reset to complite is incorrect.

Fixes: 3eb1f1ef ("usb: cdns2: Add main part of Cadence USBHS driver")
cc: stable@vger.kernel.org
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Link: https://lore.kernel.org/r/PH7PR07MB9538D56D75F1F399D0BB96F0DD922@PH7PR07MB9538.namprd07.prod.outlook.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>