Ensure title arg isn't set twice when creating 'mobile view' link

This was happening previously - but only in cases where the
wgMobileUrlTemplate variable was NOT set (e.g., not on Wikimedia wikis).
Now it happens all the time.

Bug: 56837
Change-Id: Ibdbbf461f95d48f9c522f08027ced510a05f0bff
Merge "Ensure title arg isn't set twice when creating 'mobile view' link"