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 goes back to the original issue I tried to eliminate that vmi->kpgd was sometimes really the kernel's pgd, sometimes just a random cr3. Right now this ambiguity only exists during init, which I agree, should be cleaned up more thoroughly if possible in the future.