arm: Don't clear ARM_FEATURE_PMSA for no-mpu configs

arm: Don't clear ARM_FEATURE_PMSA for no-mpu configs

Fix the handling of QOM properties for PMSA CPUs with no MPU:

Allow no-MPU to be specified by either:
 * has-mpu = false
 * pmsav7_dregion = 0
and make setting one imply the other. Don't clear the PMSA
feature bit in this situation.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 1493122030-32191-6-git-send-email-peter.maydell@linaro.org