usb: cdns3: Add support for DRD CDNSP

Patch adds support for Cadence DRD Super Speed Plus controller(CDNSP).
CDNSP DRD is a part of Cadence CDNSP controller.
The DRD CDNSP controller has a lot of difference on hardware level but on
software level is quite compatible with CDNS3 DRD. For this reason
CDNS3 DRD part of CDNS3 driver was reused for CDNSP driver.

Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Tested-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>