emulator: test 64-bit mov with immediate operand

MOV immediate instruction (opcodes 0xB8-0xBF) may take 64-bit operand.
Some hypervisor implementations assumed the operand is 32-bit.  This
should never happen because the instruction has no memory operand, but
(like the existing test_mmx_movq_mf) the testcase tricks the emulator
into executing one by mismatching the page tables and the corresponding
TLB entry.

Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>