arm64: Add feature bit to check for nested virtualization

[tylerfanelli]

Add the KVM_ARM_VCPU_HAS_EL2 feature bit, which checks for nested virtualization support.

[roypat]

Hi @tylerfanelli,
these files are autogenerated by bindgen, so manual modifications to them are a bit of a maintenance burden :(
Currently the bindings are generated from 6.2 headers, which did not include KVM_ARM_VCPU_HAS_EL2 yet. The proper way forward here would probably be to regenerate bindings from a newer kernel version, similar to what #92 is doing (discussion there was to wait until 6.9 is released and then regenerate bindings from 6.9). If you really only need this one constant, it might be easier to wait for #92 and for the meantime define the constant locally in your code

[tylerfanelli]

@roypat Thanks, I wasn't aware of that. Will do!