The reconnect attribute for chardev devices in QEMU is used to
configure the reconnect timeout in seconds.  Setting '0' value disables
the reconnect functionality thus we don't allow to set '0' for QEMU.
To disable the reconnect user should use <reconnect enabled='no'/>.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1254971Signed-off-by: NPavel Hrdina <phrdina@redhat.com>