x86, uv: fix ordering of calls to uv_system_init & uv_cpu_init

Fix problem caused by reordering of the calls to uv_cpu_init() &
uv_system_init. Originally, uv_cpu_init() was called AFTER uv_system_init.
This order was recently broken as a side-effect of other patches.

With this patch, initialization of cpu 0 is now done by the system_init
call.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>