x86/Xen: further refine add_preferred_console() invocations

As the sequence of invocations matters, add "tty" only after "hvc" when
a VGA console is available (which is often the case for Dom0, but hardly
ever for DomU).
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>

arch/x86/xen/enlighten_pv.c

@@ -1385,8 +1385,11 @@ asmlinkage __visible void __init xen_start_kernel(void)
 		xen_boot_params_init_edd();
 	}
 
-	add_preferred_console("tty", 0, NULL);
+	if (!boot_params.screen_info.orig_video_isVGA)
+		add_preferred_console("tty", 0, NULL);
 	add_preferred_console("hvc", 0, NULL);
+	if (boot_params.screen_info.orig_video_isVGA)
+		add_preferred_console("tty", 0, NULL);
 
 #ifdef CONFIG_PCI
 	/* PCI BIOS service won't work from a PV guest. */