ulib: Move ulib into its own directory

Before adding more files, create a new lib/ulib directory and put the
only existing file in there.

Signed-off-by: Simon Glass <sjg@chromium.org>

lib/ulib/Makefile

@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+# Copyright 2025 Canonical
+# Written by Simon Glass <simon.glass@canonical.com>
+
+obj-y += ulib.o

lib/ulib/ulib.c

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Simplified U-Boot library interface implementation
+ *
+ * Copyright 2025 Canonical
+ * Written by Simon Glass <simon.glass@canonical.com>
+ */
+
+#include <string.h>
+#include <version.h>
+#include <asm/global_data.h>
+#include <u-boot-lib.h>
+
+/* Static storage for global data when using simplified API */
+static struct global_data static_gd;
+
+int ulib_init(char *progname)
+{
+	int ret;
+
+	/* Initialize the U-Boot library with our static global data */
+	ret = ulib_init_with_data(progname, &static_gd);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+void ulib_uninit(void)
+{
+}
+
+const char *ulib_get_version(void)
+{
+	return PLAIN_VERSION;
+}