ui.waitReconnect() may load over HTTP instead of HTTPS

[Peter Naulls]

I see this warning in Firefox (OpenWrt 22.03):

Loading mixed (insecure) display content 
“http://192.168.113.1/luci-static/resources/icons/loading.gif?0.046104145623280135” 
on a secure page

This happens when the sysupgrade dialog is processing on an https luci. It 
doesn't cause any real harm, but it would be good to fix.

The problem is that pingDevice falls back to http only when no protocol
is specified:

	pingDevice: function(proto, ipaddr) {
		var target = '%s://%s%s?%s'.format(proto || 'http', ipaddr || 
window.location.host, L.resource('icons/loading.gif'), Math.random());


For some of the calls to ui.awaitReconnect, window.location.protocol could be
prefixed, but I think pingDevice is the correct place for a fix.