KVM: Add missing #include

Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/include/asm/kvm_para.h

 #ifndef _ASM_X86_KVM_PARA_H
 #define _ASM_X86_KVM_PARA_H
 
+#include <linux/types.h>
+
 /* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
  * should be used to determine that a VM is running under KVM.
  */