Support console over USB-to-serial

This require up-to-date UEFI bootstrap. Example usage from boot.cfg:
consdev=com4,115200
menu=NetBSD ucom0:kconsdev ucom0,115200;boot netbsd

Author: manu0401

sys/arch/x86/x86/consinit.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: consinit.c,v 1.41 2025/04/30 05:15:08 imil Exp $	*/
+/*	$NetBSD: consinit.c,v 1.42 2025/10/10 13:18:18 manu Exp $	*/
 
 /*
  * Copyright (c) 1998
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: consinit.c,v 1.41 2025/04/30 05:15:08 imil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: consinit.c,v 1.42 2025/10/10 13:18:18 manu Exp $");
 
 #include "opt_kgdb.h"
 #include "opt_puc.h"
@@ -87,6 +87,11 @@ __KERNEL_RCSID(0, "$NetBSD: consinit.c,v 1.41 2025/04/30 05:15:08 imil Exp $");
 #include <dev/pci/puccn.h>
 #endif
 
+#include "ucom.h"
+#if (NUCOM > 0)
+#include <dev/usb/ucomvar.h>
+#endif
+
 #include "ukbd.h"
 #if (NUKBD > 0)
 #include <dev/usb/ukbdvar.h>
@@ -284,6 +289,18 @@ consinit(void)
 				 COM_FREQ, COM_TYPE_NORMAL, comcnmode);
 		if (rv != 0)
 			panic("can't init serial console @%x", consinfo->addr);
+
+		return;
+	}
+#endif
+#if (NUCOM > 0)
+	if (!strcmp(console_devname, "ucom")) {
+		int unit = consinfo->addr;
+		int speed = consinfo->speed;
+
+		if (ucom_cnattach(unit, speed) != 0)
+			panic("can't init console %s", console_devname);
+
 		return;
 	}
 #endif