rpmsg: virtio_rpmsg_bus: cleanup multiple assignment to ops

Trivial cleanup: the .ops pointer is assigned twice. This patch removes the
first assignment.

Acked-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Henri Roosen <henri.roosen@ginzinger.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>