Cortex-A53 supports 40bits of address space. sbsa-ref's memory starts
above this limit.

Signed-off-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Leif Lindholm <leif@nuviainc.com>
Message-id: 20210216150122.3830863-2-marcin.juszkiewicz@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>