hmp: Fix loadvm to resume the VM on success instead of failure

hmp: Fix loadvm to resume the VM on success instead of failure

Commit f61fe11aa6f broke hmp_loadvm() by adding an incorrect negation
when converting from 0/-errno return values to a bool value. The result
is that loadvm resumes the VM now if it failed and keeps it stopped if
it failed. Fix it to restore the old behaviour and do it the other way
around.

Fixes: f61fe11aa6f7f8f0ffe4ddaa56a8108f3ab57854
Cc: qemu-stable@nongnu.org
Reported-by: Yanhui Ma <yama@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210511163151.45167-1-kwolf@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>