KVM: x86: Check .flags in kvm_cpuid_check_equal() too

kvm_cpuid_check_equal() checks for the (full) equality of the supplied
CPUID data so .flags need to be checked too.

Reported-by: Sean Christopherson <seanjc@google.com>
Fixes: c6617c61

 ("KVM: x86: Partially allow KVM_SET_CPUID{,2} after KVM_RUN")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220126131804.2839410-1-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>