Add a CAM-Newbus SDIO support module.
This works provides a newbus infrastructure for device drivers wanting
to use SDIO. On the lower end while it is connected by newbus to SDHCI,
it talks CAM using the MMCCAM framework to get to it.
This also extendes the usbdevs framework to equally create sdiodev
header files with #defines for "vendors" and "products".
Submitted by: kibab (initial work, see D12467)
Sponsored by: The FreeBSD Foundation
MFC After: 1 month