NFS: Fix typo in nomigration mount option

The option was incorrectly masking off all other options.

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Cc: stable@vger.kernel.org #3.7
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index da19c72..43cadb2 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1332,7 +1332,7 @@ static int nfs_parse_mount_options(char *raw,
 			mnt->options |= NFS_OPTION_MIGRATION;
 			break;
 		case Opt_nomigration:
-			mnt->options &= NFS_OPTION_MIGRATION;
+			mnt->options &= ~NFS_OPTION_MIGRATION;
 			break;
 
 		/*