CIFS: Replace netfid with cifs_fid struct in cifsFileInfo

This is help us to extend the code for future protocols that can use
another fid mechanism (as SMB2 that has it divided into two parts:
persistent and violatile).

Also rename variables and refactor the code around the changes.

Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

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

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

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

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

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

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

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

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

diff --cc fs/cifs/smb1ops.c
Simple merge