cpr: relax blockdev migration blockers

cpr: relax blockdev migration blockers

Some blockdevs block migration because they do not support sharing across
hosts and/or do not support dirty bitmaps.  These prohibitions do not apply
if the old and new qemu processes do not run concurrently, and if new qemu
starts on the same host as old, which is the case for cpr.  Narrow the scope
of these blockers so they only apply to normal mode.  They will not block
cpr modes when they are added in subsequent patches.

No functional change until a new mode is added.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <1698263069-406971-4-git-send-email-steven.sistare@oracle.com>