vmstate: port twl92230 device

Just don't look.  struct tm members are ints' and they are sent as uint16_t.
VMState code complains as it should.  Have to create hacky int32_as_uint16
type.  Don't ever think about copying it

Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
