i386: hvf: refactor event injection code for hvf

This patch refactors the event-injection code for hvf by using the
appropriate fields already provided by CPUX86State. At vmexit, it fills
these fields so that hvf_inject_interrupts can just retrieve them without
calling into hvf.

Signed-off-by: Sergio Andres Gomez Del Real <Sergio.G.DelReal@gmail.com>
Message-Id: <20170913090522.4022-14-Sergio.G.DelReal@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
