kvm: nVMX: Fix fault priority for VMX operations

When checking emulated VMX instructions for faults, the #UD for "IF
(not in VMX operation)" should take precedence over the #GP for "ELSIF
CPL > 0."

Suggested-by: Eric Northup <digitaleric@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>