hw/arm/armsse: Use an array for apb_ppc fields in the state structure

hw/arm/armsse: Use an array for apb_ppc fields in the state structure

Convert the apb_ppc0 and apb_ppc1 fields in the ARMSSE state struct
to use an array instead of two separate fields.  We already had one
place in the code that wanted to be able to refer to the PPC by
index, and we're about to add more code like that.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210219144617.4782-22-peter.maydell@linaro.org