KVM: selftests: Verify that kvm_cpuid2.entries layout is unchanged by KVM

In the CPUID test, verify that KVM doesn't modify the kvm_cpuid2.entries
layout, i.e. that the order of entries and their flags is identical
between what the test provides via KVM_SET_CPUID2 and what KVM returns
via KVM_GET_CPUID2.

Asserting that the layouts match simplifies the test as there's no need
to iterate over both arrays.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220614200707.3315957-17-seanjc@google.com