CIFS: Simplify byte range locking code

Split cifs_lock into several functions and let CIFSSMBLock get pid
as an argument.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

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

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

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

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