If emulate_invalid_guest_state is enabled, the emulator is called
when guest state is invalid.  Until now, we reported an mmio failure
when emulate_instruction() returned EMULATE_DO_MMIO.  This patch adds
the case where emulate_instruction() failed and an MMIO emulation
is needed.
Signed-off-by: NGuillaume Thouvenin <guillaume.thouvenin@ext.bull.net>
Signed-off-by: NAvi Kivity <avi@redhat.com>