target-arm: make PAR banked

When EL3 is running in AArch32 (or ARMv7 with Security Extensions)
PAR has a secure and a non-secure instance.

Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1416242878-876-23-git-send-email-greg.bellows@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
