usb: isp1760: add peripheral/device controller chip id

usb: isp1760: add peripheral/device controller chip id

As per the SAF1761 data sheet[0], the DcChipID register represents
the hardware version number (0001h) and the chip ID (1582h) for the
Peripheral Controller.

However as per the ISP1761 data sheet[1], the DcChipID register
represents the hardware version number (0015h) and the chip ID (8210h)
for the Peripheral Controller.

This patch adds support for both the chip ID values.

[0] http://www.nxp.com/documents/data_sheet/SAF1761.pdf
[1] http://pdf.datasheetcatalog.com/datasheets2/74/742102_1.pdf

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>