xen: Actually fix build without passthrough

Fix typo.

Fixes: acd0c941 ("xen: fix build without pci passthrough")
Signed-off-by: NAnthony PERARD <anthony.perard@citrix.com>
Message-Id: <20200619103115.254127-1-anthony.perard@citrix.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/xen/Makefile.objs

@@ -4,4 +4,4 @@ common-obj-y += xen-legacy-backend.o xen_devconfig.o xen_pvdev.o xen-bus.o xen-b
 obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
 obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_graphics.o xen_pt_msi.o
 obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt_load_rom.o
-obj-$(call $(lnot, $(CONFIG_XEN_PCI_PASSTHROUGH))) += xen_pt_stub.o
+obj-$(call lnot,$(CONFIG_XEN_PCI_PASSTHROUGH)) += xen_pt_stub.o