trivial: Remove xenfb_enabled from sysemu.h

The define is only used in one other place. Move the code there
instead of keeping this xen-specific define in sysemu.h.

Message-Id: <20200121161747.10569-1-thuth@redhat.com>
Acked-by: NPaul Durrant <paul@xen.org>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: NThomas Huth <thuth@redhat.com>

hw/xenpv/xen_machine_pv.c

@@ -60,7 +60,7 @@ static void xen_init_pv(MachineState *machine)
     xen_be_register("qnic", &xen_netdev_ops);
 
     /* configure framebuffer */
-    if (xenfb_enabled) {
+    if (vga_interface_type == VGA_XENFB) {
         xen_config_dev_vfb(0, "vnc");
         xen_config_dev_vkbd(0);
     }

include/sysemu/sysemu.h

@@ -32,7 +32,6 @@ typedef enum {
 } VGAInterfaceType;
 
 extern int vga_interface_type;
-#define xenfb_enabled (vga_interface_type == VGA_XENFB)
 
 extern int graphic_width;
 extern int graphic_height;