migration: export migration_is_running

Delete the MigrationState parameter from migration_is_running and move
it to the public API in misc.h.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Link: https://lore.kernel.org/r/1710179338-294359-5-git-send-email-steven.sistare@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>
7 files changed