qemuMonitorJSONGetMigrationStats: Don't clear @stats on failure
qemuMonitorJSONGetMigrationStats: Don't clear @stats on failure

In the qemuMonitorJSONGetMigrationStats() there's a code under
cleanup label that's clearing returned @stats if the function
returns with an error. However, transitively there's just one
caller - qemuMigrationAnyFetchStats() - and it doesn't care for
this behaviour. Drop the code to simplify the cleanup label.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>
Reviewed-by: Tim Wiederhake <da93ee425e056cfcf1ddac9fc87851b25464abf4@redhat.com>

olafhering/libvirt,crobinso/libvirt,jfehlig/libvirt,libvirt/libvirt,nertpinx/libvirt,jfehlig/libvirt,zippy2/libvirt,olafhering/libvirt,zippy2/libvirt,libvirt/libvirt,jfehlig/libvirt,zippy2/libvirt,libvirt/libvirt,olafhering/libvirt,jfehlig/libvirt,nertpinx/libvirt,libvirt/libvirt,olafhering/libvirt,zippy2/libvirt,crobinso/libvirt,nertpinx/libvirt,nertpinx/libvirt,crobinso/libvirt,crobinso/libvirt,nertpinx/libvirt