treewide: Add SPDX identifier to IETF ASN.1 modules

Per section 4.c. of the IETF Trust Legal Provisions, "Code Components"
in IETF Documents are licensed on the terms of the BSD-3-Clause license:

https://trustee.ietf.org/documents/trust-legal-provisions/tlp-5/

The term "Code Components" specifically includes ASN.1 modules:

https://trustee.ietf.org/documents/trust-legal-provisions/code-components-list-3/

Add an SPDX identifier as well as a copyright notice pursuant to section
6.d. of the Trust Legal Provisions to all ASN.1 modules in the tree
which are derived from IETF Documents.

Section 4.d. of the Trust Legal Provisions requests that each Code
Component identify the RFC from which it is taken, so link that RFC
in every ASN.1 module.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

smb: move client and server files to common directory fs/smb

Move CIFS/SMB3 related client and server files (cifs.ko and ksmbd.ko
and helper modules) to new fs/smb subdirectory:

fs/cifs --> fs/smb/client
fs/ksmbd --> fs/smb/server
fs/smbfs_common --> fs/smb/common

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>