Disables the CPU ARM_FEATURE_EL3 featuere on machine models that can be
configured to use Cortex-A9, Cortex-A15, and ARM1176 but don't officially
support EL3.  This preserves backwards compatibility.
Signed-off-by: NGreg Bellows <greg.bellows@linaro.org>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1418684992-8996-15-git-send-email-greg.bellows@linaro.org
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>