KVM: fix sparse warning in include/trace/events/kvm.h

sparse complains about
include/trace/events/kvm.h:163:1: error: directive in argument list
include/trace/events/kvm.h:167:1: error: directive in argument list
include/trace/events/kvm.h:169:1: error: directive in argument list
and sparse is right. Preprocessing directives in an argument of a
macro are undefined behaviour as of C99 6.10.3p11.

Lets use an indirection to fix this.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>