ipmi: Use proper struct reference for KCS vmstate

ipmi: Use proper struct reference for KCS vmstate

The vmstate for isa_ipmi_kcs was referencing into the kcs structure,
instead create a kcs structure separate and use that.

There were also some issues in the state transfer.  The inlen field
was not being transferred, so if a transaction was in process during
the transfer it would be messed up.  And the use_irq field was
transferred, but that should come from the configuration.

To fix this, the new VMS_VSTRUCT macros are used so the exact
version of the structure can be specified, depending on what
version was being received.  So an upgrade should work for KCS.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1524670052-28373-3-git-send-email-minyard@acm.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>