KVM: Portability: Move some includes to x86.c

Move some includes to x86.c from kvm_main.c, since the related functions
have been moved to x86.c

Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com>
Acked-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>