fat: remove parent_logstart check in fat_get_parent

fat: remove parent_logstart check in fat_get_parent

The root directory inode is added to the directory hash table in
fat_attach when mounted with nfs option.  Since root dentry never expires
until umount, fat_dget never fails to return the root inode for
subdirectories of root inode.i.e., parent_logstart cannot be zero.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ravishankar N <ravi.n1@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>