NFS: correctly report misuse of "migration" mount option.

The current test on valid use of the "migration" mount option can never
report an error as it will only do so if
    mnt->version !=4 && mnt->minor_version != 0
(and some other condition), but if that test would succeed, then the previous
test has already gone-to  out_minorversion_mismatch.

So change the && to an || to get correct semantics.
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/super.c

@@ -1614,7 +1614,7 @@ static int nfs_parse_mount_options(char *raw,
 		goto out_minorversion_mismatch;
 
 	if (mnt->options & NFS_OPTION_MIGRATION &&
-	    mnt->version != 4 && mnt->minorversion != 0)
+	    (mnt->version != 4 || mnt->minorversion != 0))
 		goto out_migration_misuse;
 
 	/*