vfio/migration: Enhance VFIO migration state tracing

vfio/migration: Enhance VFIO migration state tracing

Move trace_vfio_migration_set_state() to the top of the function, add
recover_state to it, and add a new trace event to
vfio_migration_set_device_state().

This improves tracing of device state changes as state changes are now
also logged when vfio_migration_set_state() fails (covering recover
state and device reset transitions) and in no-op state transitions to
the same state.

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>