KVM is not seen under X86 config with latest git (32 bit compile)

The KVM configuration is no longer visible in the latest git tree. It looks
like it is selected by HAVE_SETUP_PER_CPU_AREA. I've moved HAVE_KVM to
under CONFIG_X86.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>