staging: tidspbridge: remove strm_init() and strm_exit()

The strm module has a strm_init() and a strm_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>