fs/ntfs3: Sequential field availability check in mi_enum_attr()

commit 090f6127 upstream.

The code is slightly reformatted to consistently check field availability
without duplication.

Fixes: 556bdf27 ("ntfs3: Add bounds checking to mi_enum_attr()")
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>