afc: Add pairing dialogue specific message
afc: Add pairing dialogue specific message

When a pairing dialogue is shown on the device, don't tell the user that
the device is locked, rather that they need to click "Trust".

https://bugzilla.gnome.org/show_bug.cgi?id=763605

gicmo/gvfs,gicmo/gvfs,gicmo/gvfs,gicmo/gvfs