Don't add virt/kvm to KVM s390's include path, the headers in virt/kvm are
intended to be used only by other code in virt/kvm, i.e. are "private" to
the core KVM code. It's not clear that s390 *ever* included a header from
virt/kvm, i.e. odds are good the "-Ivirt/kvm" was copied from a x86's
Makefile when s390 support was first added.
The only headers in virt/kvm at the time were the x86 specific ioapic.h,
and iodev.h, neither of which shows up as an #include in the diff for the
commit range 37817f2982d0f..e976a2b997fc4.
Acked-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>