staging: exfat: remove symlink feature.

Remove symlink feature completely.

Becouse
-Uses reserved areas(defined in the Microsoft exfat specification), causing future incompatibilities.
-Not described in Microsoft exfat specifications or SD standards.
-For REMOVABLE media, causes incompatibility with other implementations.
-Not supported by other major exfat drivers.
-Not implemented symlink feature in linux FAT/VFAT.

Remove this feature completely because of serious media compatibility issues.
(Can't enable even with CONFIG)

If you have any questions about this patch, please let me know.
Reviewed-by: Takahiro Mori <Mori.Takahiro@ab.MitsubishiElectric.co.jp>
Acked-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Tetsuhiro Kohada <Kohada.Tetsuhiro@dc.MitsubishiElectric.co.jp>
Link: https://lore.kernel.org/r/20200219055727.12867-1-Kohada.Tetsuhiro@dc.MitsubishiElectric.co.jpSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>