usb: cdns2: Add main part of Cadence USBHS driver

usb: cdns2: Add main part of Cadence USBHS driver

This patch introduces the main part of Cadence USBHS driver
to Linux kernel.
To reduce the patch size a little bit, the header file gadget.h was
intentionally added as separate patch.

The Cadence USB 2.0 Controller is a highly configurable IP Core which
supports both full and high speed data transfer.

The current driver has been validated with FPGA platform. We have
support for PCIe bus, which is used on FPGA prototyping.

Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Message-ID: <20230602102644.77470-3-pawell@cadence.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>