fs/ntfs3: Fix root inode checking

Separate checking inode->i_op and inode itself.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/202302162319.bDJOuyfy-lkp@intel.com/


Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>