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 --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index ce41fee..a921b07 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -466,7 +466,7 @@
 			list_for_each(tmp2, &tcon->openFileList) {
 				netfile = list_entry(tmp2, struct cifsFileInfo,
 						     tlist);
-				if (pSMB->Fid != netfile->netfid)
+				if (pSMB->Fid != netfile->fid.netfid)
 					continue;
 
 				cFYI(1, "file id match, oplock break");