staging: most: core: remove read option from remove_link

The attribute "remove_link" returns the latest link that has been removed
of a certain channel. Since this piece information isn't particulary
useful this patch is going to remove it.

Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>