xen/arm: Blacklist sun7i UARTs

xen/arm: Blacklist sun7i UARTs

These are in the same page as the UART which is used as the Xen console. We are
not currently smart enough to avoid passing them through to the guest,
accidentally giving the guest access to the Xen console UART.

we blacklist them all, if necessary in the future we can split the list into
two halves and make a per platform decision about which half should be
blacklisted on a given platform depending on which UART is wired up as the
console.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>