util: hostcpu: Drop obsolete compatibility code

All Linux releases we support (RHEL6 era) include these
definitions.

src/util/virhostcpu.c

@@ -65,17 +65,6 @@ VIR_LOG_INIT("util.hostcpu");
 
 #define KVM_DEVICE "/dev/kvm"
 
-/* add definitions missing in older linux/kvm.h */
-#ifndef KVMIO
-# define KVMIO 0xAE
-#endif
-#ifndef KVM_CHECK_EXTENSION
-# define KVM_CHECK_EXTENSION       _IO(KVMIO,   0x03)
-#endif
-#ifndef KVM_CAP_NR_VCPUS
-# define KVM_CAP_NR_VCPUS 9       /* returns max vcpus per vm */
-#endif
-
 
 #if defined(__FreeBSD__) || defined(__APPLE__)
 static int