Restore find kpgd_method2 as a fallback.

Also fixes missing 'case' in switch statement.

I've got a Windows XP VM (32-bit, PAE, on Xen) that fails to initialize except with find_kpgd_method2, which does not appear to be attempted for live VMs after the latest PR.
This one line looks unnecessary to me, it will just get overwritten by get_kpgd_method2 anyway.