Remove mount from volume.filters
Remove the mount command from volume.filters it is not being
used anywhere.
@@ -105,7 +105,6 @@ qemu-img_convert: CommandFilter, qemu-img, root
# cinder/volume/nfs.py
stat: CommandFilter, stat, root
-mount: CommandFilter, mount, root
df: CommandFilter, df, root
du: CommandFilter, du, root
truncate: CommandFilter, truncate, root
