scripts: Add Kconfiglib v14.1.0 under scripts directory

We adopt Kconfiglib v14.1.0 sources under scripts directory so that
top-level OpenSBI makefile can directly use Kconfiglib scripts without
expecting users to install a particular version of Kconfiglib on their
build system.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Tested-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Atish Patra <atishp@rivosinc.com>
Tested-by: Atish Patra <atishp@rivosinc.com>

scripts/Kconfiglib/allnoconfig.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+
+# Copyright (c) 2018-2019, Ulf Magnusson
+# SPDX-License-Identifier: ISC
+
+"""
+Writes a configuration file where as many symbols as possible are set to 'n'.
+
+The default output filename is '.config'. A different filename can be passed
+in the KCONFIG_CONFIG environment variable.
+
+Usage for the Linux kernel:
+
+  $ make [ARCH=<arch>] scriptconfig SCRIPT=Kconfiglib/allnoconfig.py
+"""
+
+# See examples/allnoconfig_walk.py for another way to implement this script
+
+import kconfiglib
+
+
+def main():
+    kconf = kconfiglib.standard_kconfig(__doc__)
+
+    # Avoid warnings that would otherwise get printed by Kconfiglib for the
+    # following:
+    #
+    # 1. Assigning a value to a symbol without a prompt, which never has any
+    #    effect
+    #
+    # 2. Assigning values invalid for the type (only bool/tristate symbols
+    #    accept 0/1/2, for n/m/y). The assignments will be ignored for other
+    #    symbol types, which is what we want.
+    kconf.warn = False
+    for sym in kconf.unique_defined_syms:
+        sym.set_value(2 if sym.is_allnoconfig_y else 0)
+    kconf.warn = True
+
+    kconf.load_allconfig("allno.config")
+
+    print(kconf.write_config())
+
+
+if __name__ == "__main__":
+    main()