MFC: r264257, r264327, r264514

Distinguish between the different variants and configurations of Sunix
{MIO,SER}5xxxx chips instead of treating all of them as PUC_PORT_2S.
Among others, this fixes the hang seen when trying to probe the none-
existent second UART on an actually 1-port chip.

Obtained from:	NetBSD (BAR layouts)
Sponsored by:	Bally Wulff Games & Entertainment GmbH