hw/arm/armsse.c: Use correct SYS_CONFIG0 register value for SSE-300

hw/arm/armsse.c: Use correct SYS_CONFIG0 register value for SSE-300

In the SSE-300, the format of the SYS_CONFIG0 register has changed again;
pass through the correct value to the SYSINFO register block device.

We drop the old SysConfigFormat enum, which was implemented in the
hope that different flavours of SSE would share the same format;
since they all seem to be different and we now have an sse_version
enum to key off, just use that.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210219144617.4782-10-peter.maydell@linaro.org