cifs: move handling of signed connections into separate function

Move the sanity checks for signed connections into a separate function.
SMB2's was a cut-and-paste job from CIFS code, so we can make them use
the same function.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --cc fs/cifs/cifsproto.h
Simple merge

diff --cc fs/cifs/cifssmb.c
Simple merge

diff --cc fs/cifs/smb2pdu.c
Simple merge