kvm-unit-test: nVMX: Remove test_sysenter_field() and use test_canonical() instead

  ..as the latter already does what the former does.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>