qemu: only stop external devices after the domain

qemu: only stop external devices after the domain

A failure in qemuProcessLaunch would lead to qemuExtDevicesStop
being called twice - once in the cleanup section and then again
in qemuProcessStop.

However, the first one is called while the QEMU process is
still running, which is too soon for the swtpm process, because
the swtmp_ioctl command can lock up:

https://bugzilla.redhat.com/show_bug.cgi?id=1822523

Remove the first call and only leave the one in qemuProcessStop,
which is called after the QEMU process is killed.

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>