Moved clearing of vmm_initialized to avoid the case

Moved clearing of vmm_initialized to avoid the case
of unloading the module while VMs existed. This would
result in EBUSY, but would prevent further operations
on VMs resulting in the module being impossible to
unload.

Submitted by:   Tycho Nightingale (tycho.nightingale <at> plurisbusnetworks.com)
Reviewed by:	grehan, neel