fs/ntfs3: Remove a useless test in 'indx_find()'

'fnd' has been dereferenced several time before, so testing it here is
pointless.
Moreover, all callers of 'indx_find()' already have some error handling
code that makes sure that no NULL 'fnd' is passed.

So, remove the useless test.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Kari Argillander <kari.argillander@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>