fs/ntfs3: Remove unused al_delete_le

'al_delete_le' was added by:
Commit be71b5cb ("fs/ntfs3: Add attrib operations")

but has remained unused; there is an al_remove_le which seems
to be being used instead.

Remove 'al_delete_le'.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>