x86: fix VMI for early params

while fixing a different bug i moved the call to vmi_init before
early params could be parsed.

This broke the vmi specific commandline parameters.
Fix that, by moving vmi initialization after kernel has got a chance to
parse early parameters.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>