hw/misc/iotkit-secctl: Support 4 internal MPCs

hw/misc/iotkit-secctl: Support 4 internal MPCs

The SSE-200 has 4 banks of SRAM, each with its own internal
Memory Protection Controller. The interrupt status for these
extra MPCs appears in the same security controller SECMPCINTSTATUS
register as the MPC for the IoTKit's single SRAM bank. Enhance the
iotkit-secctl device to allow 4 MPCs. (If the particular IoTKit/SSE
variant in use does not have all 4 MPCs then the unused inputs will
simply result in the SECMPCINTSTATUS bits being zero as required.)

The hardcoded constant "1"s in armsse.c indicate the actual number
of SRAM MPCs the IoTKit has, and will be replaced in the following
commit.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190121185118.18550-9-peter.maydell@linaro.org