staging: tidspbridge: remove io_init() and io_exit()

The io module has a io_init() and a io_exit() whose only purpose is to
keep a reference counting which is not used at all.

This patch removes these functions and the reference count variable.

There is no functional changes.

Signed-off-by: Víctor Manuel Jáquez Leal <vjaquez@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>