staging: tidspbridge: remove trivial assert

The function dsp_deinit() always return true, so assert its output is
pointless. As consequence the variable were the returned value is stored, is
no longer needed.

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