usb: cdns2: Device side header file for CDNS2 driver

Patch defines macros, registers and structures used by
Device side driver.

Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Message-ID: <20230602102644.77470-2-pawell@cadence.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>