target-arm: Set CPU has_el3 prop during virt init

target-arm: Set CPU has_el3 prop during virt init

Adds setting of the CPU has_el3 property based on the virt machine
secure state property during initialization.  This enables/disables EL3
state during start-up.  Changes include adding an additional secure state
boolean during virt CPU initialization.  Also disables the ARM secure boot
by default.

Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
Message-id: 1418684992-8996-13-git-send-email-greg.bellows@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>